VPS4B
Description
The VPS4B (vacuolar protein sorting 4 homolog B) is a protein-coding gene located on chromosome 18.
Vacuolar protein sorting-associated protein 4B is a protein encoded by the VPS4B gene in humans. It belongs to the AAA protein family (ATPases associated with diverse cellular activities) and is homologous to the yeast Vps4 protein. Two paralogs of the yeast protein have been identified in humans. These paralogs share a high degree of amino acid similarity with each other and with yeast Vps4 and mouse proteins. Functional studies show that both human paralogs are associated with endosomal compartments and are involved in intracellular protein trafficking, similar to Vps4 in yeast. The VPS4B gene is located on chromosome 18, while the gene for its paralog, VPS4A, resides on chromosome 16.
VPS4B plays a critical role in the late stages of the endosomal multivesicular body (MVB) pathway. It recognizes ESCRT-III complexes associated with membranes and catalyzes their ATP-dependent disassembly, likely in conjunction with membrane fission. This process involves redistribution of ESCRT-III components back to the cytoplasm for subsequent rounds of MVB sorting. MVBs contain intraluminal vesicles (ILVs) formed by invagination and scission from the endosome's limiting membrane, primarily delivered to lysosomes for the degradation of membrane proteins, including stimulated growth factor receptors, lysosomal enzymes, and lipids. VPS4B, along with its paralog VPS4A, is essential for the release of SDCBP, CD63, and syndecan from exosomes.
VPS4B is also known as MIG1, SKD1, SKD1B, VPS4-2.
