β-subunits of Snf1 kinase are required for kinase function and substrate definition
β-subunits of Snf1 kinase are required for kinase function and substrate definition
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DOI：
10.1093/emboj/19.18.4936
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发表时间：
2000-09-15
期刊：
影响因子：
11.4
通讯作者：
McCartney, RR
中科院分区：
文献类型：
--
作者：
Schmidt, MC;McCartney, RR
Snf 1激酶及其哺乳动物同源物AMP活化蛋白激酶是异源三聚体酶，由催化α亚基、调节γ亚基和介导异源三聚体形成的β亚基组成。酿酒酵母（Saccharomycescerevisiae）编码3个β亚基基因SIP 1、SIP 2和GAL 83。我们在这里表明，所有三个β-亚基基因的完全和精确的删除失活的Snf 1激酶，sip 1 Δ sip 2 Δ gal 83 Δ菌株是无法derepress转化酶，生长不良的替代碳源，并未能直接磷酸化的Mig 1和Sip 4蛋白在体内。SIP 1 sip 2 Delta gal 83 Delta菌株表现出在snf 1 Delta 10菌株（Raf（-），Gly-）中观察到的Snf表型（Raf（+），Gly（-））的子集，表明单个β亚基将Snf 1激酶导向其体内靶标的子集。事实上，个别β-亚基基因的缺失导致Sip 4的诱导和磷酸化的明显差异，强烈表明β-亚基在底物定义中发挥重要作用。
The Snf1 kinase and its mammalian homolog, the AMP-activated protein kinase, are heterotrimeric enzymes Composed of a catalytic alpha-subunit, a regulatory gamma-subunit and a beta-subunit that mediates heterotrimer formation. Saccharomyces cerevisiae encodes three beta-subunit genes, SIP1, SIP2 and GAL83, Earlier studies suggested that these subunits may not be required for Snf1 kinase function. We show here that complete and precise deletion of all three beta-subunit genes inactivates the Snf1 kinase, The sip1 Delta sip2 Delta gal83 Delta strain is unable to derepress invertase, grows poorly on alternative carbon sources and fails to direct the phosphorylation of the Mig1 and Sip4 proteins in vivo. The SIP1 sip2 Delta gal83 Delta strain manifests a subset of Snf phenotypes (Raf(+), Gly(-)) observed in the snf1 Delta 10 strain (Raf(-), Gly-), suggesting that individual beta-subunits direct the Snf1 kinase to a subset of its targets in vivo. Indeed, deletion of individual beta-subunit genes causes distinct differences in the induction and phosphorylation of Sip4, strongly suggesting that the beta-subunits play an important role in substrate definition.