CHMP1B

CHMP1B, or Charged Multivesicular Body Protein 1B, is a protein encoded by the CHMP1B gene in humans. It belongs to the CHMP family of proteins, which are components of the endosomal sorting complex required for transport (ESCRT-III). ESCRT-III is essential for a variety of cellular processes involving membrane remodeling and scission, including multivesicular body (MVB) formation, cytokinesis, viral budding, and plasma membrane repair.

The CHMP family is characterized by a highly conserved core domain. Specifically, CHMP1B functions within the ESCRT-III complex to mediate the inward budding of endosomal membranes, leading to the formation of MVBs. MVBs are late endosomes containing intraluminal vesicles (ILVs), which are eventually delivered to lysosomes for degradation. This process is crucial for downregulating signaling receptors and removing damaged proteins from the cell surface.

CHMP1B, along with other ESCRT-III subunits, cycles on and off the endosomal membrane. This dynamic association is tightly regulated and involves interactions with other ESCRT components and associated proteins. The assembly and disassembly of the ESCRT-III complex is driven by ATP hydrolysis, which is facilitated by the AAA-ATPase VPS4.

Dysregulation of CHMP1B or other ESCRT components has been implicated in various diseases, including cancer, neurodegenerative disorders, and viral infections. For instance, some viruses exploit the ESCRT machinery for budding and release from infected cells. Research into CHMP1B and the ESCRT pathway is ongoing to further elucidate their roles in cellular function and disease pathogenesis.