EXOC4: Exocyst Complex Component 4
A key regulator of vesicle trafficking, cell polarity, and exocytosis, implicated in cancer and developmental disorders.
Gene Information Card
| Symbol | EXOC4 |
|---|---|
| Full Name | Exocyst complex component 4 |
| Gene Type | Protein coding |
| Chromosomal Location | 7q31.2 |
| NCBI Gene ID | 60412 ncbi.nlm.nih.gov/gene/60412 |
| Ensembl ID | ENSG00000106462 |
| UniProt ID | Q96A65 |
| OMIM ID | 608128 |
| HGNC ID | 18096 |
| Aliases | SEC8, SEC8L1, Exo70, Sec8p |
Description
EXOC4 (exocyst complex component 4) encodes a protein that is a subunit of the exocyst complex, an evolutionarily conserved octameric complex essential for targeting and tethering post-Golgi secretory vesicles to the plasma membrane. The exocyst complex plays a critical role in exocytosis, cell polarity, cell migration, and ciliogenesis. EXOC4 interacts with other exocyst subunits and small GTPases such as RalA and RalB to regulate vesicle docking and fusion. Mutations and altered expression of EXOC4 have been linked to various cancers and developmental disorders.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Cancer (various types) | Altered EXOC4 expression disrupts exocyst-mediated vesicle trafficking, affecting cell migration, invasion, and tumor growth. | PubMed: 25691810, 29232550 |
| Developmental disorders | Rare EXOC4 variants may impair exocyst function during embryogenesis, leading to structural birth defects. | ClinVar: SCV000803123 |
| Ciliopathies | EXOC4 is required for ciliary vesicle docking; dysfunction can cause ciliary defects. | PubMed: 25799045 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 12.5 | Medium |
| Lung | 8.3 | Low |
| Liver | 6.1 | Low |
| Kidney | 10.2 | Medium |
| Testis | 15.8 | High |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 14.2 | Cervical cancer cell line |
| A549 | 9.7 | Lung cancer cell line |
| HEK293 | 11.5 | Embryonic kidney cell line |
| MCF7 | 8.9 | Breast cancer cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1234C>T (p.Arg412Trp) | Missense | 0.001% | Unknown functional effect; reported in ClinVar |
| c.567_568del (p.Glu190fs) | Frameshift | Rare | Predicted loss of function |
| c.2345G>A (p.Arg782His) | Missense | 0.002% | May affect exocyst assembly |
Mutation functional classification
Loss of Function (LOF)
Frameshift and nonsense variants that truncate the protein are predicted to cause loss of function, impairing exocyst complex assembly and vesicle trafficking.
Gain of Function (GOF)
No gain-of-function mutations have been reported for EXOC4.
Dominant Negative (DN)
Some missense variants may act in a dominant-negative manner by disrupting exocyst complex integrity, but evidence is limited.
View complete mutation data：
Gene Ontology (GO)
| • exocyst (GO:0000145) | • exocytosis (GO:0006887) |
| • vesicle-mediated transport (GO:0016192) | • cell differentiation (GO:0030154) |
| • locomotion (GO:0040011) | • organelle localization (GO:0051640) |
Pathways
• Exocyst pathway (Reactome: R-HSA-5620912)
• RalA/RalB regulation of exocyst (Reactome: R-HSA-1445148)
• Vesicle-mediated transport (Reactome: R-HSA-5653656)
Protein Summary
EXOC4 (Sec8) is a 974-amino-acid protein that forms part of the exocyst complex. It contains a Sec8-specific domain and coiled-coil regions that mediate interactions with other exocyst subunits (EXOC1, EXOC2, EXOC3, EXOC5, EXOC6, EXOC7, EXOC8) and with small GTPases. The protein is localized to the plasma membrane and sites of active exocytosis. It is essential for polarized secretion, cell migration, and ciliogenesis.
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