DEFB105B

Summary

DEFB105B (defensin beta 105B, HGNC:29930) is a protein-coding gene on chromosome 8p23.1, encoding Beta-defensin 105 (Q8NG35). Has antibacterial activity.

Defensins form a family of antimicrobial and cytotoxic peptides made by neutrophils. Defensins are short, processed peptide molecules that are classified by structure into three groups: alpha-defensins, beta-defensins and theta-defensins. All beta-defensin genes are densely clustered in four to five syntenic chromosomal regions. Chromosome 8p23 contains at least two copies of the duplicated beta-defensin cluster. This duplication results in two identical copies of defensin, beta 105, DEFB105A and DEFB105B, in tail-to-tail orientation. This gene, DEFB105B, represents the more telomeric copy.

Source: NCBI Gene 504180 — RefSeq curated summary.

At a glance

• Clinical variants (ClinVar): 6 total — 2 pathogenic
• MANE Select transcript: NM_001040703

Identifiers

Gene identifiers

Field	Value
HGNC ID	HGNC:29930
Approved symbol	DEFB105B
Name	defensin beta 105B
Location	8p23.1
Locus type	gene with protein product
Status	Approved
Ensembl gene	ENSG00000186599
Ensembl biotype	protein_coding
Entrez	504180

Gene structure

Transcript identifiers

Ensembl transcripts: 1 — 1 protein_coding

ENST00000335510

RefSeq mRNA: 2 — MANE Select: NM_001040703 NM_001040703, NM_001422152

CCDS: CCDS34814

Canonical transcript exons

ENST00000335510 — 3 exons

Exon	Start	End
ENSE00001634864	7488136	7488177
ENSE00001735654	7489427	7489593
ENSE00002163206	7487679	7487790

Expression profiles

Bgee: expression breadth broad, 48 present calls, max score 50.02.

FANTOM5 (CAGE): breadth tissue_specific, TPM avg 0.0551 / max 99.0041, expressed in 1 samples.

FANTOM5 promoters (1 alternative TSS)

Promoter ID	TPM avg	Samples expressed
205050	0.0551	1

Top tissues by expression

105 total, by Bgee expression score (0-100, higher = more expressed):

Tissue	Anatomy ID	Expression score	Quality
lower esophagus mucosa	UBERON:0035834	50.02	gold quality
stromal cell of endometrium	CL:0002255	46.03	gold quality
monocyte	CL:0000576	37.43	gold quality
colonic epithelium	UBERON:0000397	37.20	gold quality
leukocyte	CL:0000738	36.54	gold quality
ventricular zone	UBERON:0003053	36.48	gold quality
cortical plate	UBERON:0005343	36.47	gold quality
bone marrow cell	CL:0002092	36.16	gold quality
ganglionic eminence	UBERON:0004023	35.49	gold quality
skeletal muscle tissue	UBERON:0001134	33.38	gold quality
hindlimb stylopod muscle	UBERON:0004252	32.15	gold quality
esophagus mucosa	UBERON:0002469	31.86	gold quality
bone marrow	UBERON:0002371	31.74	gold quality
muscle tissue	UBERON:0002385	31.06	gold quality
sural nerve	UBERON:0015488	30.93	gold quality
lymph node	UBERON:0000029	29.83	gold quality
liver	UBERON:0002107	29.73	silver quality
prefrontal cortex	UBERON:0000451	29.04	gold quality
endometrium	UBERON:0001295	28.34	silver quality
duodenum	UBERON:0002114	28.14	gold quality
tonsil	UBERON:0002372	27.05	gold quality
esophagus	UBERON:0001043	26.83	gold quality
right lobe of liver	UBERON:0001114	26.72	gold quality
blood	UBERON:0000178	26.62	silver quality
left uterine tube	UBERON:0001303	26.60	gold quality
islet of Langerhans	UBERON:0000006	26.55	gold quality
vermiform appendix	UBERON:0001154	26.42	gold quality
gall bladder	UBERON:0002110	25.98	gold quality
olfactory segment of nasal mucosa	UBERON:0005386	25.89	gold quality
placenta	UBERON:0001987	25.81	gold quality

Single-cell (SCXA)

Detected in 1 experiment(s), a significant marker in 0.

Experiment	Marker?	Max mean expression
E-ANND-3	no	0.07

Regulation

Is transcription factor: no

Literature-anchored findings (GeneRIF, showing 1)

• Defensin-beta 105 displays antimicrobial activity against S. aureus and E. coli, among other bacteria. (PMID:21861459)

Cross-species orthologs

4 orthologs

Organism	Symbol	Gene ID
mus_musculus	Defb12	ENSMUSG00000043787
mus_musculus	Defb35	ENSMUSG00000058052
rattus_norvegicus	Defb105b	ENSRNOG00000083461
rattus_norvegicus	Defb105a	ENSRNOG00000090398

Paralogs (1): DEFB105A (ENSG00000186562)

Protein

Protein identifiers

Beta-defensin 105 — Q8NG35 (reviewed: Q8NG35)

Alternative names: Beta-defensin 5, Defensin, beta 105

All UniProt accessions (2): A0A0K0K1I4, Q8NG35

UniProt curated annotations — full annotation on UniProt →

Function. Has antibacterial activity.

Subcellular location. Secreted.

Tissue specificity. Specifically expressed in testis.

Similarity. Belongs to the beta-defensin family.

RefSeq proteins (2): NP_001035793, NP_001409081 (=MANE)

Domains & families (InterPro)

ID	Name	Type
IPR025933	Beta_defensin_dom	Domain

Pfam: PF13841

UniProt features (5 total): disulfide bond 3, signal peptide 1, peptide 1

Structure

Experimental structures (PDB)

0 structures.

Predicted structure (AlphaFold)

Model	pLDDT	Fraction very-high
AF-Q8NG35-F1	72.22	0.11

Functional residue map

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

Disulfide bonds (3): 43–74, 53–67, 57–73

Function

Pathways and Gene Ontology

Reactome pathways

2 pathways

ID	Pathway
R-HSA-1461957	Beta defensins
R-HSA-1461973	Defensins

MSigDB gene sets: 9 (showing top): REACTOME_INNATE_IMMUNE_SYSTEM, GOBP_DEFENSE_RESPONSE_TO_OTHER_ORGANISM, GOBP_DEFENSE_RESPONSE_TO_BACTERIUM, GOBP_RESPONSE_TO_BACTERIUM, REACTOME_ANTIMICROBIAL_PEPTIDES, GOBP_BIOLOGICAL_PROCESS_INVOLVED_IN_INTERSPECIES_INTERACTION_BETWEEN_ORGANISMS, REACTOME_DEFENSINS, REACTOME_BETA_DEFENSINS, chr8p23

GO Biological Process (3): defense response to bacterium (GO:0042742), innate immune response (GO:0045087), defense response (GO:0006952)

GO Molecular Function (0):

GO Cellular Component (1): extracellular region (GO:0005576)

Reactome top-level categories

Rollup of top-2 pathways:

Category	Pathways
Defensins	1
Antimicrobial peptides	1

GO top-level categories

Rollup of top GO terms by namespace:

Category	Terms
defense response	1
response to bacterium	1
immune response	1
defense response to symbiont	1
response to stress	1
cellular anatomical structure	1

Protein interactions and networks

STRING

184 interactions, top by confidence (×1000):

Protein A	Protein B	Partner UniProt	Score
DEFB105B	DEFB106A	Q8N104	928
DEFB105B	DEFB104A	Q8WTQ1	914
DEFB105B	DEFB107A	Q8IZN7	883
DEFB105B	DEFB103A	P81534	880
DEFB105B	A0A0G2JN59	A0A0G2JN59	832
DEFB105B	DEFB108B	Q8NET1	815
DEFB105B	DEFB1	P60022	811
DEFB105B	DEFB4A	O15263	697
DEFB105B	PRR23D1	E9PI22	583
DEFB105B	DEFB110	Q30KQ9	570
DEFB105B	DEFB126	Q9BYW3	552
DEFB105B	DEFA5	Q01523	546
DEFB105B	USP17L4	A6NCW7	518
DEFB105B	FAM90A7	A6NKC0	515
DEFB105B	PRR23B	Q6ZRT6	509

IntAct

3 interactions, top by confidence:

A	B	Type	Score
	DEFB105A	psi-mi:“MI:0915”(physical association)	0.560
	DEFB105A	psi-mi:“MI:0915”(physical association)	0.000

BioGRID (2): DEFB105A (Two-hybrid), DEFB105B (Two-hybrid)

ESM2 similar proteins: A0A096LNP1, A4H206, A4H207, A4H208, A4H209, A4H212, A4H213, P0C8A5, P0C8B0, P0DP73, P0DP74, P59861, P82020, P82172, Q30KJ3, Q30KJ5, Q30KJ6, Q30KJ8, Q30KJ9, Q30KK8, Q30KL4, Q30KL6, Q30KM9, Q30KP5, Q30KP6, Q30KP8, Q30KQ1, Q30KQ6, Q30KQ7, Q30KQ9, Q32ZF3, Q32ZF7, Q32ZG3, Q32ZH4, Q32ZH5, Q32ZH6, Q32ZI1, Q32ZI2, Q4QY38, Q6QLQ7

Diamond homologs: A4H206, A4H207, A4H208, A4H209, Q30KQ1, Q32ZH6, Q32ZH9, Q5IAB6, Q8K4N3, Q8NG35, Q8R2I3, Q30KJ6, Q30KU3, Q30KQ6, Q32ZH8

SIGNOR signaling

0 interactions.

Disease & clinical

Clinical variants and AI predictions

ClinVar

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

Classification	Count (floor)
Pathogenic	2
Likely pathogenic	0
Uncertain significance	4
Likely benign	0
Benign	0

Top pathogenic / likely-pathogenic (2)

Variant ID	HGVS	Classification
563541	GRCh37/hg19 8p23.1(chr8:6999219-11898980)x3	Pathogenic
815083	GRCh37/hg19 8p23.1(chr8:6999219-11895232)x3	Pathogenic

SpliceAI

370 predictions. Top by Δscore:

Variant	Effect	Δscore
8:7487735:G:GT	donor_gain	0.9900
8:7487788:CAGGT:C	donor_loss	0.9900
8:7487791:G:GA	donor_loss	0.9900
8:7487791:G:GG	donor_gain	0.9900
8:7488179:T:A	donor_loss	0.9900
8:7487792:T:G	donor_loss	0.9800
8:7488132:TTAGG:T	acceptor_loss	0.9800
8:7488133:TAGG:T	acceptor_loss	0.9800
8:7488134:AG:A	acceptor_gain	0.9800
8:7488135:GG:G	acceptor_gain	0.9800
8:7487788:CAG:C	donor_gain	0.9700
8:7487789:AG:A	donor_gain	0.9700
8:7487790:GG:G	donor_gain	0.9700
8:7488134:A:AG	acceptor_gain	0.9700
8:7488135:G:GG	acceptor_gain	0.9700
8:7488135:GGGT:G	acceptor_gain	0.9700
8:7488174:TCAGG:T	acceptor_loss	0.9700
8:7488175:CAGGT:C	acceptor_loss	0.9700
8:7488176:AGG:A	acceptor_loss	0.9700
8:7488177:GGT:G	acceptor_loss	0.9700
8:7488178:GTAA:G	acceptor_loss	0.9700
8:7488179:TAA:T	acceptor_loss	0.9700
8:7489353:T:TA	acceptor_gain	0.9700
8:7489356:T:TA	acceptor_gain	0.9700
8:7487786:ATCAG:A	donor_gain	0.9600
8:7487787:TCAG:T	donor_gain	0.9600
8:7488127:T:A	acceptor_loss	0.9600
8:7488178:G:GG	donor_gain	0.9600
8:7488118:ATTTT:A	acceptor_loss	0.9500
8:7489368:T:G	acceptor_gain	0.9500

AlphaMissense

509 scored. Top likely-pathogenic:

dbSNP variants (sampled 300 via entrez): RS1004007523 (8:7486741 A>T), RS1016606954 (8:7486762 G>T), RS1021627976 (8:7489958 T>A), RS1028016386 (8:7488046 C>T), RS1045969933 (8:7486712 G>C,T), RS1055151604 (8:7486624 A>G), RS111291863 (8:7486836 CAA>C), RS112622621 (8:7486676 C>A,G,T), RS1157772048 (8:7487180 C>T), RS1158027354 (8:7487179 T>A), RS1159662519 (8:7486550 G>A), RS1159703724 (8:7489501 C>A), RS1160791754 (8:7486878 T>C), RS1161024479 (8:7489681 T>G), RS1161830108 (8:7488423 C>T)

Disease associations

OMIM: gene `` | disease phenotypes:

GenCC curated gene-disease

Mondo (0):

Orphanet (0):

HPO phenotypes

0 total (0 of 0 shown, HPO-id order):

GWAS associations

0 associations (top):

Drugs & pharmacology

Drug and pharmacology data

Is drug target: no

PharmGKB: 1 entry (VIP=true, CPIC=false)

CTD chemical–gene interactions

2 total (human), top 2 by PubMed support.

Chemical	Actions (top 5)	PubMed papers
propionaldehyde	decreases expression	1
Aflatoxin B1	increases methylation	1

Clinical trials (associated diseases)

0 trials via MONDO — disease-level, not drug-specific.