RAB11, A SMALL GTPASE ASSOCIATED WITH BOTH CONSTITUTIVE AND REGULATEDSECRETORY PATHWAYS IN PC12-CELLS

A specific polyclonal antibody was used to investigate the subcellular distribution of the small GTPase, rab11p, in the neuroendocrine cell line, PC12. We took advantage of a previously described pulse-chase pr otocol based on sulfation [1] to examine the distribution of rab11 alo ng the secretory pathway. Using the rab11 antiserum, but not serum dep leted of rab11 antibodies, we were able to specifically immunoisolate markers of the constitutive and the regulated secretory pathway in the trans-Golgi network (TGN) as well as after their exit from this compa rtment (constitutive secretory vesicles, immature, and mature secretor y granules). We therefore conclude that rab11p is associated with the TGN and with TGN-derived vesicles of both the constitutive and the reg ulated secretory pathway in PC12 cells.