CSAD

Summary

CSAD (cysteine sulfinic acid decarboxylase, HGNC:18966) is a protein-coding gene on chromosome 12q13.13, encoding Cysteine sulfinic acid decarboxylase (Q9Y600). Catalyzes the decarboxylation of L-aspartate, 3-sulfino-L-alanine (cysteine sulfinic acid), and L-cysteate to beta-alanine, hypotaurine and taurine, respectively.

This gene encodes a member of the group 2 decarboxylase family. A similar protein in rodents plays a role in multiple biological processes as the rate-limiting enzyme in taurine biosynthesis, catalyzing the decarboxylation of cysteinesulfinate to hypotaurine. Alternatively spliced transcript variants encoding multiple isoforms have been observed for this gene.

Source: NCBI Gene 51380 — RefSeq curated summary.

At a glance

• GWAS associations: 2
• Clinical variants (ClinVar): 104 total
• GTEx eGene: eQTL in 31 tissues, sQTL in 45 (q < 0.05)
• Constraint (gnomAD): pLI 0.00 (LoF-tolerant), LOEUF 0.97 (unconstrained)
• MANE Select transcript: NM_001244705
• Notable: 104 clinical variants but no curated precision-oncology (CIViC) evidence yet

Identifiers

Gene identifiers

Field	Value
HGNC ID	HGNC:18966
Approved symbol	CSAD
Name	cysteine sulfinic acid decarboxylase
Location	12q13.13
Locus type	gene with protein product
Status	Approved
Aliases	CSADC, PCAP, CSD
Ensembl gene	ENSG00000139631
Ensembl biotype	protein_coding
OMIM	616569
Entrez	51380

Gene structure

Transcript identifiers

Ensembl transcripts: 43 — 31 protein_coding, 5 nonsense_mediated_decay, 5 retained_intron, 2 protein_coding_CDS_not_defined

MANE Select: ENST00000444623

Transcript support level (Ensembl TSL; 1 = fully mRNA-supported): TSL 1: 4, TSL 3: 4, TSL 4: 6, TSL 5: 5

ENST00000444623, ENST00000267085, ENST00000379846, ENST00000379850, ENST00000424845, ENST00000424990, ENST00000437073, ENST00000453446, ENST00000454442, ENST00000461392, ENST00000472908, ENST00000475890, ENST00000483632, ENST00000485004, ENST00000490589, ENST00000490923, ENST00000491654, ENST00000498635, ENST00000548698, ENST00000885695, ENST00000885696, ENST00000885697, ENST00000885698, ENST00000885699, ENST00000885700, ENST00000885701, ENST00000885702, ENST00000885703, ENST00000943677, ENST00000943678, ENST00000943679, ENST00000943680, ENST00000943681, ENST00000943682, ENST00000943683, ENST00000943684, ENST00000943685, ENST00000943686, ENST00000943687, ENST00000943688, ENST00000943689, ENST00000997637, ENST00001013525

RefSeq mRNA: 3 — MANE Select: NM_001244705 NM_001244705, NM_001244706, NM_015989

CCDS: CCDS58235, CCDS8848

Canonical transcript exons

ENST00000444623 — 17 exons

Exon	Start	End
ENSE00001338252	53180732	53180925
ENSE00001785251	53179102	53179142
ENSE00001913209	53157663	53158684
ENSE00003463051	53172346	53172436
ENSE00003495409	53159623	53159712
ENSE00003497571	53161127	53161191
ENSE00003503589	53161273	53161389
ENSE00003516757	53170072	53170126
ENSE00003541373	53160120	53160319
ENSE00003560294	53171882	53171988
ENSE00003570312	53172522	53172648
ENSE00003591127	53160763	53160844
ENSE00003611504	53171326	53171441
ENSE00003652284	53159887	53159938
ENSE00003652892	53173728	53173770
ENSE00003659168	53170423	53170502
ENSE00003675020	53173345	53173476

Expression profiles

Bgee: expression breadth ubiquitous, 263 present calls, max score 98.21.

FANTOM5 (CAGE): breadth ubiquitous, TPM avg 13.4827 / max 235.7852, expressed in 1781 samples.

Highest expression (Bgee): uterine tube, lobe of liver, mucosa of stomach, ovary, omental fat pad.

Genetic regulation across tissues (GTEx eQTL / sQTL)

CSAD is an eGene in GTEx v10 — its expression is genetically regulated (eQTL) in 31 tissues and its splicing (sQTL) in 45 (q < 0.05). Strongest associations first; slope = normalized effect of the lead variant’s alternative allele.

showing 20 of 76 significant tissue × QTL associations:

Tissue	QTL	q-value	Slope	Lead variant
Artery Tibial	sqtl	3.9e-40	-3.09	12:53177904:T:C
Nerve Tibial	sqtl	1.2e-39	-2.77	12:53194396:A:C
Lung	sqtl	2.9e-36	+3.11	12:53177904:T:C
Adipose Subcutaneous	sqtl	1.9e-34	-2.64	12:53194396:A:C
Skin Sun Exposed Lower leg	sqtl	7.4e-33	-2.93	12:53195141:T:G
Colon Transverse	sqtl	4.6e-29	-3.04	12:53195141:T:G
Cells Cultured fibroblasts	sqtl	1.4e-28	-3.20	12:53194396:A:C
Pancreas	sqtl	2.6e-28	-3.24	12:53177904:T:C
Esophagus Mucosa	sqtl	4.8e-26	-2.93	12:53177904:T:C
Whole Blood	sqtl	1.8e-24	-2.25	12:53195141:T:G
Colon Sigmoid	sqtl	5.0e-23	+3.21	12:53177904:T:C
Breast Mammary Tissue	sqtl	2.2e-22	+3.19	12:53195141:T:G
Thyroid	sqtl	2.1e-21	-2.44	12:53195141:T:G
Adipose Visceral Omentum	sqtl	1.0e-20	+2.94	12:53195141:T:G
Artery Aorta	sqtl	2.7e-20	-3.23	12:53177904:T:C
Skin Not Sun Exposed Suprapubic	sqtl	2.9e-20	-2.55	12:53177904:T:C
Cells EBV-transformed lymphocytes	sqtl	7.3e-20	-3.03	12:53195141:T:G
Esophagus Muscularis	sqtl	1.7e-19	+2.71	12:53195141:T:G
Stomach	sqtl	2.9e-19	-2.95	12:53177904:T:C
Heart Left Ventricle	sqtl	4.2e-17	-3.17	12:53177904:T:C

FANTOM5 promoters

9 alternative TSS:

Promoter ID	TPM avg	Samples expressed
131207	5.3508	1415
131208	3.3988	1252
131210	2.2197	800
131205	1.0602	633
131206	1.0321	501
131209	0.2739	84
131204	0.0732	8
131202	0.0537	7
131203	0.0204	8

Top tissues by expression

showing 100 of 284 tissues by Bgee expression score (0-100, higher = more expressed):

Tissue	Anatomy ID	Expression score	Quality
right uterine tube	UBERON:0001302	98.21	gold quality
right lobe of liver	UBERON:0001114	97.68	gold quality
mucosa of stomach	UBERON:0001199	97.66	gold quality
left ovary	UBERON:0002119	97.58	gold quality
omental fat pad	UBERON:0010414	97.55	gold quality
right hemisphere of cerebellum	UBERON:0014890	97.52	gold quality
peritoneum	UBERON:0002358	97.50	gold quality
endocervix	UBERON:0000458	97.45	gold quality
right ovary	UBERON:0002118	97.44	gold quality
subcutaneous adipose tissue	UBERON:0002190	97.42	gold quality
cerebellar hemisphere	UBERON:0002245	97.40	gold quality
adipose tissue of abdominal region	UBERON:0007808	97.38	gold quality
cerebellar cortex	UBERON:0002129	97.28	gold quality
peripheral nervous system	UBERON:0000010	97.20	gold quality
nerve	UBERON:0001021	97.20	gold quality
tibial nerve	UBERON:0001323	97.20	gold quality
ectocervix	UBERON:0012249	97.02	gold quality
minor salivary gland	UBERON:0001830	96.71	gold quality
body of pancreas	UBERON:0001150	96.64	gold quality
esophagogastric junction muscularis propria	UBERON:0035841	96.58	gold quality
right lobe of thyroid gland	UBERON:0001119	96.49	gold quality
skin of abdomen	UBERON:0001416	96.48	gold quality
body of uterus	UBERON:0009853	96.48	gold quality
left lobe of thyroid gland	UBERON:0001120	96.38	gold quality
apex of heart	UBERON:0002098	96.37	gold quality
descending thoracic aorta	UBERON:0002345	96.34	gold quality
adenohypophysis	UBERON:0002196	96.30	gold quality
skin of leg	UBERON:0001511	96.24	gold quality
ascending aorta	UBERON:0001496	96.17	gold quality
adipose tissue	UBERON:0001013	96.15	gold quality
thoracic aorta	UBERON:0001515	96.14	gold quality
metanephros cortex	UBERON:0010533	96.14	gold quality
left coronary artery	UBERON:0001626	96.13	gold quality
lower esophagus muscularis layer	UBERON:0035833	96.07	gold quality
lower esophagus	UBERON:0013473	96.06	gold quality
left uterine tube	UBERON:0001303	96.04	gold quality
popliteal artery	UBERON:0002250	96.02	gold quality
tibial artery	UBERON:0007610	96.01	gold quality
aorta	UBERON:0000947	95.99	gold quality
body of stomach	UBERON:0001161	95.99	gold quality
right coronary artery	UBERON:0001625	95.94	gold quality
muscle layer of sigmoid colon	UBERON:0035805	95.91	gold quality
right adrenal gland cortex	UBERON:0035827	95.83	gold quality
cerebellum	UBERON:0002037	95.80	gold quality
blood vessel layer	UBERON:0004797	95.80	gold quality
C1 segment of cervical spinal cord	UBERON:0006469	95.73	gold quality
small intestine Peyer’s patch	UBERON:0003454	95.56	gold quality
lower esophagus mucosa	UBERON:0035834	95.48	gold quality
right adrenal gland	UBERON:0001233	95.44	gold quality
right testis	UBERON:0004534	95.27	gold quality
pituitary gland	UBERON:0000007	95.24	gold quality
connective tissue	UBERON:0002384	95.19	gold quality
left testis	UBERON:0004533	95.18	gold quality
coronary artery	UBERON:0001621	94.89	gold quality
transverse colon	UBERON:0001157	94.85	gold quality
thyroid gland	UBERON:0002046	94.85	gold quality
left adrenal gland cortex	UBERON:0035825	94.79	gold quality
sural nerve	UBERON:0015488	94.70	gold quality
right frontal lobe	UBERON:0002810	94.58	gold quality
upper lobe of left lung	UBERON:0008952	94.48	gold quality
left adrenal gland	UBERON:0001234	94.46	gold quality
right lung	UBERON:0002167	94.46	gold quality
esophagus	UBERON:0001043	94.40	gold quality
spinal cord	UBERON:0002240	94.24	gold quality
fundus of stomach	UBERON:0001160	94.06	gold quality
adrenal cortex	UBERON:0001235	93.97	gold quality
mouth mucosa	UBERON:0003729	93.93	gold quality
spleen	UBERON:0002106	93.87	gold quality
granulocyte	CL:0000094	93.76	gold quality
stomach	UBERON:0000945	93.73	gold quality
esophagus mucosa	UBERON:0002469	93.47	gold quality
small intestine	UBERON:0002108	93.33	gold quality
zone of skin	UBERON:0000014	93.32	gold quality
right atrium auricular region	UBERON:0006631	93.23	gold quality
upper lobe of lung	UBERON:0008948	93.23	gold quality
liver	UBERON:0002107	93.17	gold quality
gall bladder	UBERON:0002110	92.91	gold quality
vagina	UBERON:0000996	92.83	gold quality
anterior cingulate cortex	UBERON:0009835	92.82	gold quality
saliva-secreting gland	UBERON:0001044	92.80	gold quality
cingulate cortex	UBERON:0003027	92.64	gold quality
Brodmann (1909) area 9	UBERON:0013540	92.33	gold quality
adrenal gland	UBERON:0002369	92.29	gold quality
ovary	UBERON:0000992	92.24	gold quality
testis	UBERON:0000473	91.87	gold quality
prostate gland	UBERON:0002367	91.86	gold quality
amygdala	UBERON:0001876	91.70	gold quality
cortical plate	UBERON:0005343	91.68	gold quality
rectum	UBERON:0001052	91.35	gold quality
stromal cell of endometrium	CL:0002255	91.31	gold quality
cardiac atrium	UBERON:0002081	90.95	gold quality
monocyte	CL:0000576	90.81	gold quality
nucleus accumbens	UBERON:0001882	90.76	gold quality
gastrocnemius	UBERON:0001388	90.67	gold quality
caudate nucleus	UBERON:0001873	90.66	gold quality
mucosa of transverse colon	UBERON:0004991	90.66	gold quality
dorsolateral prefrontal cortex	UBERON:0009834	90.43	gold quality
mononuclear cell	CL:0000842	90.38	gold quality
colonic epithelium	UBERON:0000397	90.33	gold quality
anatomical system	UBERON:0000467	90.33	gold quality

Single-cell (SCXA)

Detected in 1 experiment(s), a significant marker in 1.

Experiment	Marker?	Max mean expression
E-ANND-3	yes	5.24

HPA expression

RNA tissue specificity: Low tissue specificity

showing 60 of 80 HPA tissues / cells by nTPM:

Tissue / cell	Axis	nTPM	Protein (IHC)
Choroid plexus	tissue	59.3
Skin 1	tissue	55.2	medium
Epididymis	tissue	47.5	medium
Liver	tissue	42.5	medium
Adipose tissue	tissue	41.0	low
Pituitary gland	tissue	36.4
Bone marrow	tissue	36.3	low
Vagina	tissue	33.9	medium
Hippocampus	tissue	31.2	not detected
Prostate	tissue	30.1	medium
Nucleus accumbens	tissue	28.2
Endometrium 1	tissue	27.8	medium
Locus coeruleus	tissue	27.7
Cerebellum	tissue	26.4	medium
Postcentral gyrus	tissue	26.1
Olfactory bulb	tissue	25.5
Breast	tissue	25.1	medium
Salivary gland	tissue	24.3	medium
Caudate putamen	tissue	20.8
Frontal cortex	tissue	20.4
Spleen	tissue	19.4	medium
Ovary	tissue	18.8	not detected
Basal ganglia	tissue	18.8	low
Seminal vesicle	tissue	18.2	medium
Cerebral cortex	tissue	18.0	low
Insular cortex	tissue	18.0
Amygdala	tissue	17.9
Skeletal muscle	tissue	17.8	medium
Retrosplenial and cingulate cortex	tissue	17.8
Smooth muscle	tissue	17.7	high
Gallbladder	tissue	17.6	medium
Retrosplenial cortex	tissue	17.6
Temporal cortex	tissue	17.5
Lymph node	tissue	17.4	medium
Hippocampal formation	tissue	16.7
Entorhinal cortex	tissue	16.7
Ventral forebrain	tissue	16.6
Occipital cortex	tissue	16.3
Somatosensory cortex	tissue	16.1
Duodenum	tissue	16.0	medium
Septum	tissue	15.9
Prefrontal cortex	tissue	15.7
Putamen	tissue	15.7
Testis	tissue	15.6	medium
Stomach 1	tissue	15.3	medium
Motor cortex	tissue	15.2
Retina	tissue	15.0
Rectum	tissue	14.6	medium
Appendix	tissue	14.6	high
Fallopian tube	tissue	14.5	medium
Small intestine	tissue	14.3	medium
Lung	tissue	14.2	medium
Corpus callosum	tissue	14.0
Periaqueductal gray	tissue	14.0
Parathyroid gland	tissue	13.7	medium
Thyroid gland	tissue	13.7	medium
Hypothalamus	tissue	13.6
Adrenal gland	tissue	13.1	medium
Cervix	tissue	12.9	high
Tonsil	tissue	12.8	high

Brain sub-regions (HPA Brain Atlas): detected in 192; highest nTPM — Parieto-temporal junction (white matter) (62.6), Temporal white matter (57.0), Corpus callosum, genu (white matter) (46.6), Corpus callosum, splenium (white matter) (45.9), Cerebellar white matter (43.7).

Regulation

Is transcription factor: no

miRNA regulators (miRDB)

Targeting CSAD by miRDB confidence (max_score; target_count = how many genes the miRNA targets in total — lower means more specific).

showing 30 of 40 miRNAs:

miRNA	Max score	Avg score	miRNA target_count
HSA-MIR-30A-5P	100.00	76.31	3233
HSA-MIR-30B-5P	100.00	76.29	3248
HSA-MIR-30C-5P	100.00	76.29	3248
HSA-MIR-30D-5P	100.00	76.32	3233
HSA-MIR-30E-5P	100.00	76.32	3242
HSA-MIR-4776-3P	100.00	68.73	1340
HSA-MIR-340-5P	100.00	72.50	4437
HSA-MIR-8068	99.98	73.85	2376
HSA-MIR-548AT-5P	99.96	70.83	2666
HSA-MIR-551B-5P	99.96	71.28	3493
HSA-MIR-590-3P	99.96	74.34	6478
HSA-MIR-6845-3P	99.94	66.88	1439
HSA-MIR-3143	99.93	71.96	3104
HSA-MIR-1305	99.91	71.43	3443
HSA-MIR-3671	99.90	73.04	3897
HSA-MIR-95-5P	99.89	72.17	3973
HSA-MIR-4728-5P	99.85	69.39	4718
HSA-MIR-6785-5P	99.82	68.68	4428
HSA-MIR-4307	99.82	70.45	3374
HSA-MIR-6844	99.82	70.69	2423
HSA-MIR-202-5P	99.78	67.65	991
HSA-MIR-149-3P	99.72	68.22	3963
HSA-MIR-6883-5P	99.69	68.05	3785
HSA-MIR-7161-5P	99.68	68.92	1592
HSA-MIR-5197-5P	99.64	69.08	1494
HSA-MIR-1249-5P	99.61	66.55	2049
HSA-MIR-6797-5P	99.61	66.55	2084
HSA-MIR-330-3P	99.41	69.95	2521
HSA-MIR-504-3P	99.30	67.18	1745
HSA-MIR-4505	99.27	67.81	2678

Functional genomics

gnomAD constraint: pLI 5.23e-13, LOEUF 0.972, missense Z 0.781 — population loss-of-function intolerance (pLI ≥ 0.9 = LoF-intolerant; lower LOEUF = more constrained). gnomAD

Regional missense constraint (gnomAD RMC): no regional variation along ENST00000444623 — one region, missense o/e 0.95.

Literature-anchored findings (GeneRIF, showing 2)

• The presence of cysteine inhibited ADC, CSAD and GDC activity. (PMID:22718265)
• taurine biosynthesis in vertebrates involves two structurally related PLP-dependent decarboxylases (cysteine sulfinic acid decarboxylase and glutamic acid decarboxylase like 1) (PMID:26327310)

Cross-species orthologs

4 orthologs

Organism	Symbol	Gene ID
danio_rerio	csad	ENSDARG00000026348
mus_musculus	Csad	ENSMUSG00000023044
rattus_norvegicus	Csad	ENSRNOG00000011573
drosophila_melanogaster	b	FBGN0000153

Paralogs (7): GAD1 (ENSG00000128683), DDC (ENSG00000132437), GAD2 (ENSG00000136750), HDC (ENSG00000140287), GADL1 (ENSG00000144644), SGPL1 (ENSG00000166224), PDXDC1 (ENSG00000179889)

Mouse-model phenotypes

Observed phenotypes of the mouse ortholog (MGI:2180098) from MGI (Alliance of Genome Resources) — knockout/mutant phenotypes, ranked by annotation count. 1 distinct phenotype terms.

Mouse phenotype (MP)	Records
neonatal lethality, incomplete penetrance	1

Additional cross-species homologs

Sequence homologs in species beyond Ensembl Compara’s model organisms, by Diamond local protein alignment (% sequence identity; best hit per species). Lower-identity rows are more distant homologs. The matched accessions’ gene symbols aren’t in biobtree yet, so each row shows the UniProt accession.

Organism	UniProt	Identity	Method
Canis lupus familiaris	A0PA85	99.8%	Diamond
Felis catus	P14748	99.8%	Diamond
Pongo abelii	Q5R7S7	99.8%	Diamond
Pan troglodytes	Q5IS68	99.5%	Diamond
Sus scrofa	P48319	99.0%	Diamond
Bos taurus	Q0VCA1	99.0%	Diamond
Scaptodrosophila lebanonensis	O96571	89.6%	Diamond
Cavia porcellus	P22781	86.8%	Diamond
Xenopus tropicalis	Q28D99	78.2%	Diamond
Acinetobacter baumannii	Q43908	75.5%	Diamond
Methanopyrus kandleri AV19	Q8TV92	50.1%	Diamond
Penicillium expansum	A0A0A2IDH4	43.0%	Diamond
Metarhizium robertsii ARSEF 23	E9FCP7	40.1%	Diamond
Fusarium graminearum PH-1	I1RV23	39.1%	Diamond
Sinorhizobium meliloti 1021	Q9Z3R1	37.2%	Diamond
Psilocybe cubensis	A0A4P1LYB6	35.2%	Diamond

Genomic neighbors (locus context)

Genes flanking this one on the chromosome (NCBI/Entrez gene neighborhood). Positional context only — some neighbors share regulatory elements (bidirectional promoters, antisense/overlapping transcripts), but chromosomal adjacency is not itself a functional relationship (see Interactions for that).

Symbol	Type	Entrez
ZNF740	protein-coding	283337
ITGB7	protein-coding	3695
RARG	protein-coding	5916
SLC61A1	protein-coding	84975

Protein

Protein identifiers

Cysteine sulfinic acid decarboxylase — Q9Y600 (reviewed: Q9Y600)

Alternative names: Aspartate 1-decarboxylase, Cysteine-sulfinate decarboxylase, Sulfinoalanine decarboxylase

All UniProt accessions (9): C9JTU8, E9PFW9, Q9Y600, F6XLJ2, F8VV11, F8WCW3, H3BQ59, H3BTP4, J3KPG9

UniProt curated annotations — full annotation on UniProt →

Function. Catalyzes the decarboxylation of L-aspartate, 3-sulfino-L-alanine (cysteine sulfinic acid), and L-cysteate to beta-alanine, hypotaurine and taurine, respectively. The preferred substrate is 3-sulfino-L-alanine. Does not exhibit any decarboxylation activity toward glutamate.

Subunit / interactions. Homodimer.

Tissue specificity. Expressed in liver and brain. Also expressed in both astrocytes and neurons, but lower levels are expressed in astrocytes.

Pathway. Organosulfur biosynthesis; taurine biosynthesis; hypotaurine from L-cysteine: step 2/2.

Similarity. Belongs to the group II decarboxylase family.

Isoforms (3)

UniProt ID	Names	Canonical?
Q9Y600-1	1, Long	yes
Q9Y600-2	2, Short
Q9Y600-3	3

RefSeq proteins (3): NP_001231634, NP_001231635, NP_057073 (=MANE)

Domains & families (InterPro)

ID	Name	Type
IPR002129	PyrdxlP-dep_de-COase	Domain
IPR015421	PyrdxlP-dep_Trfase_major	Homologous_superfamily
IPR015424	PyrdxlP-dep_Trfase	Homologous_superfamily

Pfam: PF00282

Enzyme classification (BRENDA)

• EC 4.1.1.29 — sulfinoalanine decarboxylase (BRENDA: 29 organisms, 27 substrates, 36 inhibitors, 24 Km, 5 kcat entries)

Substrate kinetics (BRENDA)

11 substrates with measured Km, best-characterized 11. Km ranges are aggregated across organisms/conditions.

Substrate	Km (mM)	Measurements
CYSTEINE SULFINATE	0.037–0.94	5
L-CYSTEIC ACID	0.22–4	3
3-SULFINO-L-ALANINE	1.1–1.56	2
CYSTEINE SULFINIC ACIDS	0.18–0.2	2
CYSTEINE SULFONATE	0.536–0.644	2
L-CYSTEINE SULFINATE	1.14–1.16	2
L-CYSTEINE SULFINIC ACID	0.14–2	2
ASP	11	1
CYSTEIC ACID	0.66	1
CYSTEINE SULFINIC ACID	2.07	1
GLU	2.9	1

Catalyzed reactions (Rhea)

• 3-sulfino-L-alanine + H(+) = hypotaurine + CO2 (RHEA:16877)
• L-aspartate + H(+) = beta-alanine + CO2 (RHEA:19497)
• L-cysteate + H(+) = taurine + CO2 (RHEA:25221)

UniProt features (49 total): helix 26, strand 12, sequence conflict 4, turn 3, splice variant 2, chain 1, modified residue 1

Structure

Experimental structures (PDB)

1 structures by resolution:

PDB	Title	Method	Resolution (Å)
2JIS	Human cysteine sulfinic acid decarboxylase (CSAD) in complex with PLP.	X-RAY DIFFRACTION	1.6

Predicted structure (AlphaFold)

Model	pLDDT	Fraction very-high
AF-Q9Y600-F1	96.67	0.97

Human Protein Atlas

Protein class: Enzymes, ENZYME proteins, Lyases, Metabolic proteins, Predicted intracellular proteins, Plasma proteins

Protein evidence: Evidence at protein level

Subcellular location (HPA, imaging): endoplasmic reticulum; plasma membrane; vesicles

Antibody reliability (HPA): IH approved · IF approved

Functional residue map

Curated UniProt residues grouped by drug-discovery relevance — catalytic, ligand-binding, modification, and mutation-validated positions. Source: UniProtKB sequence features.

Post-translational modifications (1)

Type	Positions
N6-(pyridoxal phosphate)lysine	305

Function

Pathways and Gene Ontology

Reactome pathways

0 curated (TAS) of 4; 0 disease pathways. Curated-first; evidence = TAS (manually curated) vs IEA (electronic inference).

4 pathways:

ID	Pathway	Evidence
R-HSA-1614558	Degradation of cysteine and homocysteine	electronic
R-HSA-1430728	Metabolism	—
R-HSA-71291	Metabolism of amino acids and derivatives	—
R-HSA-1614635	Sulfur amino acid metabolism	—

MSigDB gene sets: 192 (showing top): RORA1_01, GOBP_ALPHA_AMINO_ACID_METABOLIC_PROCESS, AREB6_01, FOXO1_01, GOBP_ORGANIC_ACID_BIOSYNTHETIC_PROCESS, FOXD3_01, GOBP_SMALL_MOLECULE_BIOSYNTHETIC_PROCESS, GOBP_SULFUR_COMPOUND_BIOSYNTHETIC_PROCESS, GOBP_SULFUR_COMPOUND_CATABOLIC_PROCESS, YY1_02, KEGG_TAURINE_AND_HYPOTAURINE_METABOLISM, TGCTGAY_UNKNOWN, GOBP_ORGANIC_ACID_CATABOLIC_PROCESS, GOBP_ORGANIC_ACID_METABOLIC_PROCESS, LEE_LIVER_CANCER_DENA_DN

GO Biological Process (3): taurine biosynthetic process (GO:0042412), L-cysteine catabolic process (GO:0019448), carboxylic acid metabolic process (GO:0019752)

GO Molecular Function (6): aspartate 1-decarboxylase activity (GO:0004068), sulfinoalanine decarboxylase activity (GO:0004782), pyridoxal phosphate binding (GO:0030170), lyase activity (GO:0016829), carbon-carbon lyase activity (GO:0016830), carboxy-lyase activity (GO:0016831)

GO Cellular Component (1): cytoplasm (GO:0005737)

Reactome top-level categories

3 top-level categories:

Category	Pathways
Sulfur amino acid metabolism	1
Metabolism of amino acids and derivatives	1
Metabolism	1

GO top-level categories

14 GO namespaces:

Category	Terms
carboxy-lyase activity	2
taurine metabolic process	1
alkanesulfonate biosynthetic process	1
sulfur amino acid catabolic process	1
amino acid catabolic process	1
proteinogenic amino acid catabolic process	1
oxoacid metabolic process	1
anion binding	1
vitamin B6 binding	1
catalytic activity	1
lyase activity	1
carbon-carbon lyase activity	1
intracellular anatomical structure	1
cellular anatomical structure	1

Protein interactions and networks

STRING

showing 15 of 1,123 interactions by confidence (×1000):

Protein A	Protein B	Partner UniProt	Score
CSAD	CDO1	P78513	823
CSAD	ADO	Q96SZ5	696
CSAD	SLC6A6	P31641	682
CSAD	CTH	P32929	518
CSAD	BHMT	Q93088	484
CSAD	H7C2H4	H7C2H4	469
CSAD	P0DN79	P0DN79	469
CSAD	VWCE	Q96DN2	430
CSAD	PIPOX	Q9P0Z9	429
CSAD	MAT1A	Q00266	413
CSAD	THNSL2	Q86YJ6	413
CSAD	SUOX	P51687	411
CSAD	AHCY	P23526	389
CSAD	GOT2	P00505	372
CSAD	MTR	Q99707	368

IntAct

Human interaction partners of CSAD in IntAct, one row per partner (best MIscore; records = supporting IntAct interaction records).

12 partners by confidence:

Partner	Interaction type	MIscore	Records
BMP2K	physical association	0.490	2
SH2B1	physical association	0.490	2
ANXA1	physical association	0.370	1
ANXA7	physical association	0.370	1
CDKN1A	physical association	0.370	1
GSK3B	physical association	0.370	1
NR1H2	physical association	0.370	1
PIN1	physical association	0.370	1
RAP1B	physical association	0.370	1
RCC1	physical association	0.370	1
SMN1	physical association	0.370	1
TK1	physical association	0.370	1

BioGRID (19 interactions; top human partners by supporting records): ANXA1 (Two-hybrid), ANXA7 (Two-hybrid), CDKN1A (Two-hybrid), CHMP4B (Affinity Capture-MS), FZR1 (Affinity Capture-MS), GSK3B (Two-hybrid), MOV10 (Affinity Capture-RNA), NR1H2 (Two-hybrid), NUDT21 (Affinity Capture-RNA), PIN1 (Two-hybrid), RAP1B (Two-hybrid), RCC1 (Two-hybrid), REV3L (Synthetic Growth Defect), SH2B1 (Two-hybrid), SMN1 (Two-hybrid)

SIGNOR signaling

2 signaling interactions:

A	Effect	B	Mechanism
CSAD	“down-regulates quantity”	L-aspartate(1-)	“chemical modification”
CSAD	“up-regulates quantity”	“beta-alanine zwitterion”	“chemical modification”

Disease & clinical

Genetic variants

Variant evidence for CSAD: 104 ClinVar records (0 pathogenic / likely pathogenic); 2 GWAS associations.

ClinVar

104 variants total. Per-class counts are floors (≥ shown; pagination cap):

Classification	Count (floor)
Pathogenic	0
Likely pathogenic	0
Uncertain significance	74
Likely benign	4
Benign	3

AlphaMissense

1,226 missense substitutions predicted likely pathogenic (of 3,204 scored), across 329 residues. Top 20 hotspot residues, ranked by the number of likely-pathogenic substitutions (of those reachable by a single-nucleotide change), then by mean score:

Residue	Likely-pathogenic substitutions	Mean am_pathogenicity	Max am_pathogenicity
D348	8	0.985	0.995
D273	8	0.973	0.983
H191	8	0.971	0.992
F337	8	0.969	0.998
D361	8	0.967	0.988
H271	8	0.965	0.991
D254	8	0.962	0.976
H304	8	0.924	0.985
D340	8	0.916	0.970
F185	8	0.903	0.992
F124	8	0.897	0.966
N302	8	0.880	0.989
F465	8	0.850	0.975
F148	8	0.845	0.962
F414	8	0.816	0.964
C356	7	0.974	0.992
W269	7	0.964	0.988
E119	7	0.961	0.991
E128	7	0.957	0.993
F89	7	0.949	0.994

HPA cancer prognostics

RNA cancer specificity: Low cancer specificity

Human Protein Atlas survival analysis — favorable = higher expression predicts better survival.

5 prognostic cancer types:

Cancer	Prognostic	p-value
Kidney Renal Clear Cell Carcinoma (TCGA)	unfavorable	3.83e-05
Liver Hepatocellular Carcinoma (TCGA)	favorable	0.000109
Pancreatic Adenocarcinoma (TCGA)	favorable	0.000246
Liver Hepatocellular Carcinoma (validation)	favorable	0.000508
Pancreatic Adenocarcinoma (validation)	unfavorable	0.000989

Disease associations

OMIM: gene MIM:616569 | disease phenotypes:

GWAS associations

2 associations:

Study	Trait	p-value
GCST007433_7	Fulminant type 1 diabetes	8e-9
GCST001762_313	Obesity-related traits	2e-6

EFO canonical traits (from GWAS)

1 canonical traits:

EFO ID	Trait name
EFO:0005000	leptin measurement

Drugs & pharmacology

Drug and pharmacology data

Is drug target: no

PharmGKB: 1 entry (CPIC guideline: no)

CTD chemical–gene interactions

40 total (human), top 30 by PubMed support.

Chemical	Actions (top 5)	PubMed papers
bisphenol F	increases expression, affects cotreatment, decreases methylation	2
bisphenol A	decreases expression, affects cotreatment	2
Air Pollutants	affects expression, increases abundance, increases expression	2
Arsenic	affects cotreatment, decreases expression, increases abundance, affects methylation	2
Dexamethasone	increases expression, affects cotreatment, decreases expression	2
Cyclosporine	decreases expression	2
Aflatoxin B1	affects methylation, decreases expression	2
Cadmium Chloride	increases abundance, increases expression	2
Particulate Matter	increases abundance, increases expression	2
aristolochic acid I	increases expression	1
sotorasib	affects cotreatment, increases expression	1
triphenyl phosphate	affects expression	1
beta-lapachone	increases expression	1
mono-(2-ethylhexyl)phthalate	increases expression	1
sodium arsenite	affects cotreatment, decreases expression, increases abundance	1
perfluorooctanoic acid	increases expression	1
manganese chloride	decreases expression, increases abundance, affects cotreatment	1
entinostat	increases expression	1
candoxin	decreases expression	1
bisphenol B	increases expression	1
bisphenol S	affects cotreatment, decreases expression	1
trametinib	affects cotreatment, increases expression	1
NVP-BKM120	affects cotreatment, increases expression	1
bisphenol AF	increases expression	1
Fulvestrant	affects cotreatment, decreases methylation	1
Glyphosate	increases expression	1
Vehicle Emissions	increases abundance, increases expression	1
Cadmium	increases abundance, increases expression	1
Cannabidiol	decreases expression	1
Indomethacin	affects cotreatment, decreases expression, increases expression	1

Cellosaurus cell lines

1 cell lines: 1 cancer cell line

First 10 cell lines (id-ordered, not curated):

Cellosaurus	Name	Category	Sex
CVCL_B1PC	Abcam HeLa CSAD KO	Cancer cell line	Female

Clinical trials (associated diseases)

Via MONDO — disease-level, not drug-specific.

12 trials:

NCT	Phase	Status	Title
NCT03414970	Phase 3	ACTIVE_NOT_RECRUITING	Hypofractionated Radiation Therapy After Mastectomy in Preventing Recurrence in Patients With Stage IIa-IIIa Breast Cancer
NCT00461344	Phase 2	TERMINATED	Docetaxel + Doxorubicin as Neoadjuvant Chemotherapy in Patients With Breast Cancer
NCT07499999	Phase 2	NOT_YET_RECRUITING	Randomized Double-Blind Phase II Trial of Baby Exemestane Versus Baby Tamoxifen in Post-Menopausal Women at High Risk for Breast Cancer
NCT00637364	Phase 1/2	SUSPENDED	High Intensity Focused Ultrasound Tumor Treatment for Pancreatic Cancer Pain
NCT02779855	Phase 1/2	COMPLETED	Talimogene Laherparepvec in Combination With Neoadjuvant Chemotherapy in Triple Negative Breast Cancer
NCT01753908	Early Phase 1	COMPLETED	Broccoli Sprout Extract in Treating Patients With Breast Cancer
NCT01796041	Early Phase 1	COMPLETED	Intraoperative Imaging of Breast Cancer With Indocyanine Green
NCT07628634	Early Phase 1	RECRUITING	Feasibility Study on the Effect of a Methionine-Reduced Diet on Serum Levels in Pts w/ Solid Tumors
NCT01208974	Not specified	COMPLETED	Nipple-Areola Complex (NAC) Irradiation After Nipple-Sparing Mastectomy and Reconstruction
NCT01875198	Not specified	TERMINATED	Oncologic Impact of Splenectomy-omitting Radical Pancreatectomy in Well-selected Left-sided Pancreatic Cancer
NCT03543397	Not specified	UNKNOWN	MRI in Ductal Carcinoma in Situ (DCIS)
NCT03834532	Not specified	COMPLETED	Living Well After Breast Surgery