CHMP1A Antibody – Mouse Polyclonal

This gene encodes a member of the CHMP/Chmp family of proteins which are involved in multivesicular body sorting of proteins to the interiors of lysosomes. The initial prediction of the protein sequence encoded by this gene suggested that the encoded protein was a metallopeptidase. The nomenclature has been updated recently to reflect the correct biological function of this encoded protein. Several transcripts encoding different isoforms have been found for this gene. [provided by RefSeq, Dec 2012]

Function: Probable peripherally associated component of the endosomal sorting required for transport complex III (ESCRT-III) which is involved in multivesicular bodies (MVBs) formation and sorting of endosomal cargo proteins into MVBs. 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. The MVB pathway appears to require the sequential function of ESCRT-O, -I,-II and -III complexes. ESCRT-III proteins mostly dissociate from the invaginating membrane before the ILV is released. The ESCRT machinery also functions in topologically equivalent membrane fission events, such as the terminal stages of cytokinesis and the budding of enveloped viruses (HIV-1 and other lentiviruses). ESCRT-III proteins are believed to mediate the necessary vesicle extrusion and/or membrane fission activities, possibly in conjunction with the AAA ATPase VPS4. Involved in cytokinesis. Involved in recruiting VPS4A and/or VPS4B to the midbody of dividing cells. May also be involved in chromosome condensation. Targets the Polycomb group (PcG) protein BMI1/PCGF4 to regions of condensed chromatin. May play a role in stable cell cycle progression and in PcG gene silencing. Ref.1 Ref.2 Ref.7 Ref.13 Ref.17

Subunit structure: Probable peripherally associated component of the endosomal sorting required for transport complex III (ESCRT-III). ESCRT-III components are thought to multimerize to form a flat lattice on the perimeter membrane of the endosome. Several assembly forms of ESCRT-III may exist that interact and act sequentally. Self-associates. Interacts with CHMP1B. Interacts with VPS4A. Interacts with VPS4B. Interacts with PHF1. Interacts with IST1. Interacts with MITD1. Ref.7 Ref.8 Ref.9 Ref.12 Ref.13 Ref.17

Subcellular location: Cytoplasm. Endosome membrane; Peripheral membrane protein. Nucleus matrix. Note: The cytoplasmic form is partially membrane-associated and localizes to early endosomes. The nuclear form remains associated with the chromosome scaffold during mitosis. On overexpression, it localizes to nuclear bodies characterized by nuclease-resistant condensed chromatin. Ref.2 Ref.7

Tissue specificity: Expressed in placenta, cultured skin fibroblasts and in osteoblast cell line MG-63. Ref.1

Induction: By muristerone. Ref.2

Involvement in disease: Pontocerebellar hypoplasia 8 (PCH8) [MIM:614961]: An autosomal recessive neurodevelopmental disorder characterized by severe psychomotor retardation, abnormal movements, hypotonia, spasticity, and variable visual defects. Brain MRI shows pontocerebellar hypoplasia, decreased cerebral white matter, and a thin corpus callosum.Note: The disease is caused by mutations affecting the gene represented in this entry. Ref.15

Sequence similarities: Belongs to the SNF7 family.

Caution: Was originally (Ref.1) thought to be a metalloprotease (PRSM1). This was based on a wrong translation of the ORF which gave rise to a putative protein of 318 AA containing a pattern reminiscent of zinc metalloproteases.

Sequence caution: The sequence AAC50775.1 differs from that shown. Reason: Erroneous translation. Wrong choice of frame.The sequence BAA07557.1 differs from that shown. Reason: Erroneous translation. Wrong choice of frame.