期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 276, 期 52, 页码 49083-49092出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M108763200
关键词
-
The mechanism by which ubiquitous adenine nucleotide-gated K(IR)6.0(4)/SUR4 channels link membrane excitability with cellular metabolism is controversial. Is a decreased sensitivity to inhibitory ATP required, or is the Mg-ADP/ATP-dependent stimulatory action of the ATPase, sulfonylurea receptor (SUR), on K-IR sufficient to elicit a physiologically significant open channel probability? To evaluate the roles of nucleotide inhibition versus stimulation, we compared K(IR)6.1-based K-NDP channels with K(IR)6.2-based K-ATP channels and all possible K(IR)6.1/6.2 hybrids. Although K-NDP channels are thought to be poorly sensitive to inhibitory ATP and to require Mg-nucleotide diphosphates for activity, we demonstrate that, like K-ATP, and hybrid channels, they are inhibited with an IC50(ATP) 100-fold lower than [ATP](i). K(IR)6.1 is, however, more efficiently stimulated by SUR than K(IR)6.2, thus providing a mechanism for differential nucleotide regulation, in addition to the known differential interactions of Mg-nucleotides with SUR isoforms. The on-cell and spontaneous activities of K-NDP, K-ATP, and hybrid channels identified in native cells, are different; thus, their similar IC50(ATP) values argue the regulatory beta SUR subunits play a preeminent role in coupling excitation to metabolism and pose questions about the physiologic significance of models, which assume the ATP insensitivity of open K(IR)s.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据