Pannexin1 Channels Contain a Glycosylation Site That Targets the Hexamer to the Plasma Membrane

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 Pannexin...

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Bibliographic Details
Published in:The Journal of biological chemistry 2007-10, Vol.282 (43), p.31733-31743
Main Authors: Boassa, Daniela, Ambrosi, Cinzia, Qiu, Feng, Dahl, Gerhard, Gaietta, Guido, Sosinsky, Gina
Format: Article
Language:English
Subjects:
Asparagine - metabolism
Biotinylation
Cell Line
Cell Membrane - metabolism
Cell Membrane - ultrastructure
Connexins - chemistry
Connexins - genetics
Connexins - metabolism
Connexins - ultrastructure
Cross-Linking Reagents - pharmacology
Dose-Response Relationship, Drug
Electrophysiology
Glycosylation
Humans
Immunohistochemistry
Ion Channels - ultrastructure
Kidney - cytology
Models, Biological
Mutation
Nerve Tissue Proteins
Protein Processing, Post-Translational
Protein Structure, Secondary
Succinimides - pharmacology
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Summary: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.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M702422200