Trafficking dynamics of glycosylated pannexin 1 proteins.

Pannexins are mammalian orthologs of innexins and have a predicted topological folding pattern similar to that of connexins, except they are glycosylated. Rat pannexin 1 is glycosylated at N254 and this residue is important for plasma membrane targeting. Here we demonstrate that cell surface expression levels of the rat pannexin 1 N254Q mutant are rescued by coexpression with the wild-type protein. In paired Xenopus oocytes, the functional effect of this rescue is inconsequential; however, cell surface deglycosylation by PNGase F significantly enhanced functional gap junction formation. In mammalian cells, wild-type oligomers traffic at a slower rate than Myc-or tetracysteine domain-tagged versions, a behavior opposite to that of tagged connexins. The temporal differences of Panx1 trafficking correlate with spatial differences of intracellular localizations induced by Golgi blockage by Brefeldin-A or glycosylation prevention by tunicamycin. Therefore, Panx1 has kinetics and dynamics that make it unique to serve distinct functions separate from connexin-based channels.