Rab GTPase-binding effector protein 1

RABEP1 (Rab GTPase-binding effector protein 1) is a Rab effector protein that functions as a linker between gamma-adaptin and the small GTPases RAB4A and RAB5A (UniProt: Q15276). It plays a central role in endocytic membrane fusion and recycling endosome trafficking, and also regulates trafficking of ion channels such as KCNH1 and the PKD1:PKD2 complex from the endoplasmic reticulum through the secretory pathway.

RABEP1 operates within vesicular transport pathways essential for cellular homeostasis. The protein forms regulatory complexes with RABGEF1 to facilitate nucleotide exchange on RAB5A, thereby modulating endosomal dynamics and cargo recycling. No disease associations are documented in the UniProt knowledgebase.

RABEP1 is downregulated in Alzheimer's disease brain. Analysis of post-mortem AD tissue versus age-matched controls using quantitative proteomics detected reduced RABEP1 levels with a mean log2 fold-change of −0.77 (Chaparral AD proteomics). This downregulation may reflect impaired endocytic trafficking and membrane dynamics characteristic of AD pathophysiology.