The small GTPase rab5 functions as a regulatory factor in the early endocytic pathway

Cecilia Bucci, Robert G. Parton, Ian H. Mather, Henk Stunnenberg, Kai Simons, Bernard Hoflack, Marino Zerial

Research output: Contribution to journalArticlepeer-review

1206 Citations (Scopus)


We have investigated the in vivo functional role of rab5, a small GTPase associated with the plasma membrane and early endosomes. Wild-type rab5 or rab5ile 133, a mutant protein defective in GTP binding, was overexpressed in baby hamster kidney cells. In cells expressing the rab5ile 133 protein, the rate of endocytosis was decreased by 50% compared with normal, while the rate of recycling was not significantly affected. The morphology of early endosomes was also drastically changed by the mutant protein, which induced accumulation of small tubules and vesicles at the periphery of the cell. Surprisingly, overexpression of wild-type rab5 accelerated the uptake of endocytic markers and led to the appearance of atypically large early endosomes. We conclude that rab5 is a ratelimiting component of the machinery regulating the kinetics of membrane traffic in the early endocytic pathway.

Original languageEnglish
Pages (from-to)715-728
Number of pages14
Issue number5
Publication statusPublished - 4 Sept 1992
Externally publishedYes


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