PT  - JOURNAL ARTICLE
AU  - Yu-Hsin Chiu
AU  - Claudia Alvarez-Baron
AU  - Eun Young Kim
AU  - Stuart E. Dryer
TI  - Dominant-Negative Regulation of Cell Surface Expression by a Pentapeptide Motif at the Extreme COOH Terminus of an Slo1 Calcium-Activated Potassium Channel Splice Variant
AID  - 10.1124/mol.109.061929
DP  - 2010 Apr 01
TA  - Molecular Pharmacology
PG  - 497--507
VI  - 77
IP  - 4
4099  - http://molpharm.aspetjournals.org/content/77/4/497.short
4100  - http://molpharm.aspetjournals.org/content/77/4/497.full
SO  - Mol Pharmacol2010 Apr 01; 77
AB  - Large-conductance Ca2+-activated K+ (BKCa) channels regulate the physiology of many cell types. A single vertebrate gene variously known as Slo1, KCa1.1, or KCNMA1 encodes the pore-forming subunits of BKCa channel but is expressed in a potentially very large number of alternative splice variants. Two splice variants of Slo1, Slo1VEDEC and Slo1QEERL, which differ at the extreme COOH terminus, show markedly different steady-state expression levels on the cell surface. Here we show that Slo1VEDEC and Slo1QEERL can reciprocally coimmunoprecipitate, indicating that they form heteromeric complexes. Moreover, coexpression of even small amounts of Slo1VEDEC markedly reduces surface expression of Slo1QEERL and total Slo1 as indicated by cell-surface biotinylation assays. The effects of Slo1VEDEC on steady-state surface expression can be attributed primarily to the last five residues of the protein based on surface expression of motif-swapped constructs of Slo1 in human embryonic kidney (HEK) 293T cells. In addition, the presence of the VEDEC motif at the COOH terminus of Slo1 channels is sufficient to confer a dominant-negative effect on cell surface expression of itself or other types of Slo1 subunits. Treating cells with short peptides containing the VEDEC motif increased surface expression of Slo1VEDEC channels transiently expressed in HEK293T cells and increased current through endogenous BKCa channels in mouse podocytes. Slo1VEDEC and Slo1QEERL channels are removed from the HEK293T cell surface with similar kinetics and to a similar extent, which suggests that the inhibitory effect of the VEDEC motif is exerted primarily on forward trafficking into the plasma membrane.Copyright © 2010 The American Society for Pharmacology and Experimental Therapeutics