Molecular cloning of the mouse homologue of Rab3c

Small GTP-binding proteins of the Rab subfamily are key regulators of intra cellular vesicle transport. Here we report the isolation of a cDNA clone en coding the complete Rab3c isoform from mouse embryo using a degenerative PC R-based approach. Multiple sequence alignment revealed that the predicted a mino acid sequence was identical to the previously identified rat Rab3c iso form and 98% identical to the published bovine Rab3c GTPase from brain. Fur thermore by in situ hybridisation, Rab3c mRNA was detectable within various regions of the brain, cartilage and highly enriched within intestinal vill i of foetal tissues. Chondrocytes in the hypertrophic zone, but not reserve or proliferative zones, expressed high levels of Rab3c. This pattern of ex pression corresponds with the genesis of matrix vesicles during endochondra l ossification. In all, our results suggest that in addition to its functio nal role during regulated secretion in brain, Rab3c may play a part in matr ix vesicle trafficking during skeletal development.