Rab7 has been shown to regulate the late steps of the endocytic pathway. In bone-resorbing
osteoclasts, it is involved in formation of the ruffled border, which is a late endosomal-like
compartment in the plasma membrane. Here we report a new Rab7-interacting protein,
Rac1, another small GTPase protein that binds to the GTP-form of Rab7 as found with a two-
hybrid system. We demonstrate further that Rab7 colocalizes with Rac1 at the fusion zone of
the ruffled border in bone-resorbing osteoclasts. In other cell types, such as fibroblast-like …