RAB27B Gene: Function, Expression, and Clinical Significance

RAB27B is a member of the RAS oncogene family of small GTPases. It plays a critical role in intracellular vesicle trafficking, particularly in regulated exocytosis. RAB27B is involved in the secretion of granules in various cell types, including platelets, melanocytes, and cytotoxic T lymphocytes. It functions by interacting with effector proteins such as Slp4-a (granuphilin) and Slac2-b (exophilin-5). Mutations in RAB27B are associated with Griscelli syndrome type 2 (GS2), a rare autosomal recessive disorder characterized by partial albinism and immunodeficiency. Additionally, RAB27B has been implicated in cancer progression, where its overexpression can promote tumor invasion and metastasis.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• RAB27B-mediated exocytosis

• Regulated secretory pathway

• Melanosome transport

• Exosome biogenesis and secretion

RAB27B is a small GTPase that cycles between an active GTP-bound and inactive GDP-bound state. It regulates vesicle trafficking by recruiting effector proteins to specific membranes. In platelets, it controls dense granule release; in melanocytes, it mediates melanosome transport; in cytotoxic T cells, it is essential for granule exocytosis. Its role in cancer involves promoting exosome secretion, which can remodel the tumor microenvironment and facilitate metastasis.