Title :
Pannexin 1 and
pannexin 3 are
glycoproteins that exhibit many distinct characteristics from the connexin family of gap junction
proteins
Abstract :
- Pannexins are mammalian orthologs of the invertebrate gap junction proteins innexins and thus have been proposed to play a role in gap junctional intercellular communication
- Localization of exogenously expressed pannexin 1 ( Panx1 ) and pannexin 3 3 (Panx3 ), together with pharmacological studies, revealed a cell surface distribution profile and life cycle dynamics that were distinct from connexin 43 ( Cx43 , encoded by Gja1 )
- Furthermore, N-glycosidase treatment showed that both Panx1 (approximately 41-48 kD species) and Panx3 (approximately 43 kD) were glycosylated, whereas N-linked glycosylation-defective mutants exhibited a decreased ability to be transported to the cell surface
- Tissue surveys revealed the expression of Panx1 in several murine tissues--including in cartilage, skin, spleen and brain--whereas Panx3 expression was prevalent in skin and cartilage with a second higher-molecular-weight species present in a broad range of tissues
- Tissue-specific localization patterns of Panx1 and Panx3 ranging from distinct cell surface clusters to intracellular profiles were revealed by immunostaining of skin and spleen sections
- Finally, functional assays in cultured cells transiently expressing Panx1 and Panx3 were incapable of forming intercellular channels , but assembled into functional cell surface channels
- Collectively, these studies show that Panx1 and Panx3 have many characteristics that are distinct from Cx43 and that these proteins probably play an important biological role as single membrane channels