Rabex-5 Is a Rab22 Effector and Mediates a Rab22-Rab5 Signaling Cascade in Endocytosis

• DOI: 10.1091/mbc.e09-06-0453
• Publication Date: 2009-09-17T01:29:40Z
• Authors: Huaiping Zhu; Zhimin Liang; Guangpu Li
• Keywords: Rab

Rabex-5 targets to early endosomes and functions as a guanine nucleotide exchange factor for Rab5. Membrane targeting is critical activate Rab5 on in the cell. Here, we report identification of Rab22 binding site direct recruitment activation Rab5, establishing Rab22-Rab5 signaling relay promote endosome fusion. guanosine 5'-O-(3-thio)triphosphate-loaded form, but not diphosphate-loaded binds endosomal domain (residues 81-230) pull-down assays. Rab22-containing endosomes, knockdown by short hairpin RNA abrogates membrane In addition, coexpression shows synergistic enlargement this synergy dependent Rabex-5, providing further support collaboration two Rab GTPases regulation dynamics. This novel Rab22-Rabex-5-Rab5 cascade functionally important endocytosis degradation epidermal growth factor.