VPS4A
Domain
The MIT domain serves as an adapter for ESCRT-III proteins. It forms an asymmetric three-helix bundle that binds amphipathic MIM (MIT interacting motif) helices along the groove between MIT helices 2 and 3 present in a subset of ESCRT-III proteins thus establishing the canonical MIM-MIT interaction. In an extended conformation along the groove between helices 1 and 3, also binds to a type-2 MIT interacting motif (MIM2).
Function
Involved in late steps of the endosomal multivesicular bodies (MVB) pathway. Recognizes membrane-associated ESCRT-III assemblies and catalyzes their disassembly, possibly in combination with membrane fission. Redistributes the ESCRT-III components to the cytoplasm for further rounds of MVB sorting. MVBs contain intraluminal vesicles (ILVs) that are generated by invagination and scission from the limiting membrane of the endosome and mostly are delivered to lysosomes enabling degradation of membrane proteins, such as stimulated growth factor receptors, lysosomal enzymes and lipids. It is required for proper accomplishment of various processes including the regulation of endosome size, primary cilium organization, mitotic spindle organization, chromosome segregation, and nuclear envelope sealing and spindle disassembly during anaphase (PubMed:33186545). Involved in cytokinesis: retained at the midbody by ZFYVE19/ANCHR and CHMP4C until abscission checkpoint signaling is terminated at late cytokinesis. It is then released following dephosphorylation of CHMP4C, leading to abscission (PubMed:24814515). VPS4A/B are required for the exosomal release of SDCBP, CD63 and syndecan (PubMed:22660413). Critical for normal erythroblast cytokinesis and correct erythropoiesis (PubMed:33186543).
(Microbial infection) In conjunction with the ESCRT machinery also appears to function in topologically equivalent membrane fission events, such as the terminal stages of cytokinesis and enveloped virus budding (HIV-1 and other lentiviruses).
Involvement in disease
CIMDAG syndrome
CIMDAG
An autosomal dominant syndrome characterized by global developmental delay, severely impaired intellectual development, poor or absent speech, microcephaly, growth retardation, poor motor skills with inability to walk, hypotonia and spasticity, and cataracts. Cerebral and cerebellar atrophy, thin corpus callosum, and delayed myelination are apparent on brain imaging. Affected individuals show hematologic abnormalities mostly consistent with congenital dyserythropoietic anemia.
None
The disease may be caused by variants affecting the gene represented in this entry.
Sequence Similarities
Belongs to the AAA ATPase family.
Tissue Specificity
Ubiquitously expressed.
Cellular localization
- Late endosome membrane
- Peripheral membrane protein
- Midbody
- Cytoplasm
- Cytoskeleton
- Spindle
- Membrane-associated in the prevacuolar endosomal compartment. Localizes to the midbody of dividing cells, interaction with ZFYVE19/ANCHR mediates retention at midbody (PubMed:24814515). Localized in two distinct rings on either side of the Flemming body.
Alternative names
VPS4, VPS4A, Vacuolar protein sorting-associated protein 4A, Protein SKD2, VPS4-1, hVPS4