Role of C-terminus of Kir7.1 potassium channel in cell-surface expression.
Inward rectifier K+ channel Kir7.1 is predominantly expressed on the plasma membrane of a variety of ion-transporting epithelia. The electrophysiological property of Kir7.1 has been well characterized but the mechanism underlying the plasma-membrane targeting remains elusive. To address this issue, we examined the effect of deletion and site-directed mutagenesis on the plasma-membrane localization of Kir7.1 in Madin-Darby canine kidney cells by immunofluorescence microscopy and cell-surface biotinylation. Although deletions of up to 37 amino acid residues from the C-terminus had no effect, further deletion resulted in accumulation of the mutant proteins in intracellular membranes. No sequence motif for subcellular targeting was found in the distal C-terminal region. The cell-surface expression of the deletion mutant lacking 38 or 40 C-terminal residues was restored by addition of one or three alanine residues, respectively, to the C-terminus end. These results suggest that the C-terminal length plays an important role in the plasma-membrane localization of Kir7.1.
Tateno
Toru
T
Department of Clinical and Molecular Endocrinology, Tokyo Medical and Dental University Graduate School, 1-5-45, Yushima, Tokyo 113-8519, Japan.
Nakamura
Nobuhiro
N
Hirata
Yukio
Y
Hirose
Shigehisa
S
D000595:Amino Acid Sequence; D000818:Animals; D019921:Biotinylation; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D004285:Dogs; D017353:Gene Deletion; D008969:Molecular Sequence Data; D024661:Potassium Channels, Inwardly Rectifying / Q000737:chemistry* / Q000378:metabolism*; D051381:Rats; D016415:Sequence Alignment; D013997:Time Factors
C489477:Kir7.1 channel; D024661:Potassium Channels, Inwardly Rectifying