Journal
JOURNAL OF GENERAL PHYSIOLOGY
Volume 119, Issue 6, Pages 581-591Publisher
ROCKEFELLER UNIV PRESS
DOI: 10.1085/jgp.20028562
Keywords
K+ current; K-ATP; PIP2; Kir6.2; PH domain
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Funding
- NHLBI NIH HHS [R01 HL054171, HL 54171] Funding Source: Medline
- NIDDK NIH HHS [DK 20579, P60 DK020579, P30 DK020579] Funding Source: Medline
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All members of the inward rectifiier K+ (Kir) channel family are activated by phosphoinositides and other amphiphilic lipids. To further elucidate the mechanistic basis, we examined the membrane association of Kir6.2 fragments of K-ATP channels, and the effects of site-directed mutations of these fragments and full-length Kir6.2 on membrane association and K-ATP channel activity, respectively. GFP-tagged Kir6:2 COOH terminus and GFP-tagged pleckstrin homology domain from phospholipase C delta1 both associate with isolated membranes, and association of each is specifically reduced by muscarinic ml receptor-mediated phospholipid depletion. Kir COOH termini are predicted to contain multiple beta-strands and a conserved alpha-helix (residues similar to306-311 in Kir6.2). Systematic mutagenesis of D307-F315 reveals a critical role of E308, 1309, W311 and F315, consistent with residues lying on one side of a a-helix. Together with systematic mutation of conserved charges, the results define critical determinants of a conserved domain that underlies phospholipid interaction in Kir channels.
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