Title :
Pannexin1 channels contain a glycosylation
site that targets the hexamer to the plasma membrane
Abstract :
- Pannexins are newly discovered channel proteins expressed in many different tissues and abundantly in the vertebrate central nervous system
- Based on membrane topology, folding and secondary structure prediction, pannexins are proposed to form gap junction-like structures
- We show here that Pannexin1 forms a hexameric channel and reaches the cell surface but, unlike connexins, is N-glycosylated
- Using site-directed mutagenesis we analyzed three putative N-linked glycosylation sites and examined the effects of each mutation on channel expression
- We show for the first time that Pannexin1 is glycosylated at Asn-254 and that this residue is important for plasma membrane targeting
- The glycosylation of Pannexin1 at its extracellular surface makes it unlikely that two oligomers could dock to form an intercellular channel
- Ultrastructural analysis by electron microscopy confirmed that Pannexin1 junctional areas do not appear as canonical gap junctions
- Rather, Pannexin1 channels are distributed throughout the plasma membrane
- We propose that N-glycosylation of Pannexin1 could be a significant mechanism for regulating the trafficking of these membrane proteins to the cell surface in different tissues