Differential asparagine-linked glycosylation of voltage-gated K+ channels in mammalian brain and in transfected cells.
Glycosylation of ion channel proteins dramatically impacts channel function. Here we characterize the asparagine (N)-linked glycosylation of voltage-gated K+ channel alpha subunits in rat brain and transfected cells. We find that in brain Kv1.1, Kv1.2 and Kv1.4, which have a single consensus glycosylation site in the first extracellular interhelical domain, are N-glycosylated with sialic acid-rich oligosaccharide chains. Kv2.1, which has a consensus site in the second extracellular interhelical domain, is not N-glycosylated. This pattern of glycosylation is consistent between brain and transfected cells, providing compelling support for recent models relating oligosaccharide addition to the location of sites on polytopic membrane proteins. The extent of processing of N-linked chains on Kv1.1 and Kv1.2 but not Kv1.4 channels expressed in transfected cells differs from that seen for native brain channels, reflecting the different efficiencies of transport of K+ channel polypeptides from the endoplasmic reticulum to the Golgi apparatus. These data show that addition of sialic acid-rich N-linked oligosaccharide chains differs among highly related K+ channel alpha subunits, and given the established role of sialic acid in modulating channel function, provide evidence for differential glycosylation contributing to diversity of K+ channel function in mammalian brain.
Shi
G
G
Department of Biochemistry and Cell Biology and Institute for Cell and Developmental Biology, State University of New York at Stony Brook, Stony Brook, NY 11794, USA.
Trimmer
J S
JS
D000818:Animals; D001216:Asparagine / Q000378:metabolism*; D001923:Brain Chemistry; D019556:COS Cells / Q000378:metabolism; D016384:Consensus Sequence; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D051662:Kv1.1 Potassium Channel; D051663:Kv1.2 Potassium Channel; D051665:Kv1.4 Potassium Channel; D019158:N-Acetylneuraminic Acid / Q000032:analysis; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009844:Oligosaccharides / Q000737:chemistry; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D011499:Protein Processing, Post-Translational; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection
C496972:Kcna2 protein, rat; C496979:Kcna4 protein, rat; D051663:Kv1.2 Potassium Channel; D051665:Kv1.4 Potassium Channel; D009419:Nerve Tissue Proteins; D009844:Oligosaccharides; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011993:Recombinant Fusion Proteins; D051662:Kv1.1 Potassium Channel; D001216:Asparagine; D019158:N-Acetylneuraminic Acid