Molecular cloning of the mouse homologue of Rab3c.

Small GTP-binding proteins of the Rab subfamily are key regulators of intracellular vesicle transport. Here we report the isolation of a cDNA clone encoding the complete Rab3c isoform from mouse embryo using a degenerative PCR-based approach. Multiple sequence alignment revealed that the predicted amino acid sequence was identical to the previously identified rat Rab3c isoform and 98% identical to the published bovine Rab3c GTPase from brain. Furthermore by in situ hybridisation, Rab3c mRNA was detectable within various regions of the brain, cartilage and highly enriched within intestinal villi of foetal tissues. Chondrocytes in the hypertrophic zone, but not reserve or proliferative zones, expressed high levels of Rab3c. This pattern of expression corresponds with the genesis of matrix vesicles during endochondral ossification. In all, our results suggest that in addition to its functional role during regulated secretion in brain, Rab3c may play a part in matrix vesicle trafficking during skeletal development.