Glycosylation of shaker potassium channel protein in insect cell culture and in Xenopus oocytes.
We have studied the glycosylation of Shaker K+ channel protein made in two expression systems: an insect cell culture line and amphibian oocytes. In both systems, two potential sites for N-linked glycosylation were modified. The modified sites were located between the first and second putative transmembrane segments, S1 and S2. Although the same sites appeared to be glycosylated in both systems, the fraction of protein glycosylated and the size, structure, or composition of the oligosaccharide chains added were quite different. The results indicate that the S1-S2 loop is extracellular, consistent with a cytoplasmic location for the N-terminus and a transmembrane disposition for hydrophobic segment S1. We have also shown that glycosylation occurs in two stages in oocytes, generating an immature and a mature form of Shaker protein. However, glycosylation is not required either for the assembly of functional channels or for their transport to the cell surface.
Santacruz-Toloza
L
L
Department of Physiology, School of Medicine, University of California, Los Angeles 90024-1751.
Huang
Y
Y
John
S A
SA
Papazian
D M
DM
D000595:Amino Acid Sequence; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D002478:Cells, Cultured; D006031:Glycosylation; D051662:Kv1.1 Potassium Channel; D008969:Molecular Sequence Data; D009036:Moths; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D014981:Xenopus; D029867:Xenopus Proteins
D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D029867:Xenopus Proteins; C084069:kcna1 protein, Xenopus; D051662:Kv1.1 Potassium Channel