Phosphorylation of yeast plasma membrane H+-ATPase by casein kinase I.
(1996) Journal of Biological Chemistry — Vol. 271, n° 50, p. 32064-32072 (1996)
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- Abstract
- The plasma membrane H+-ATPase of Saccharomyces cerevisiae is subject to phosphorylation by a casein kinase I activity in vitro. We show this casein kinase I activity to result from the combined function of YCK1 and YCK2, two highly similar and plasma membrane-associated casein kinase I homologues. First, H+-ATPase phosphorylation is severely impaired in the plasma membrane of YCK-deficient yeast strains. Furthermore, the wild-type level of the phosphoprotein is restored by the addition of purified mammalian casein kinase I to the mutant membranes. We used the H+-ATPase as well as a synthetic peptide substrate that contains a phosphorylation site for casein kinase I to compare kinase activity in membranes prepared from yeast cells grown in the presence or absence of glucose. The addition of glucose results in increased H+-ATPase activity which is associated with a decline in the phosphorylation level of the enzyme. Mutations in both YCK1 and YCK2 affect this regulation, suggesting that H+-ATPase activity is modulated by glucose via a combination of a "down-regulating" casein kinase I activity and another, yet uncharacterized, "up-regulating" kinase activity. Biochemical mapping of phosphorylated H+-ATPase identifies a major phosphopeptide that contains a consensus phosphorylation site (Ser-507) for casein kinase I. Site-directed mutagenesis of this consensus sequence indicates that Glu-504 is important for glucose-induced decrease in the apparent Km for ATP.
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Estrada, E., Agostinis, P., Vandenheede, J. R., Goris, J., Merlevede, W., François, J., Goffeau, A., & Ghislain, M. (1996). Phosphorylation of yeast plasma membrane H+-ATPase by casein kinase I. Journal of Biological Chemistry, 271(50), 32064-32072. https://hdl.handle.net/2078.5/135450 (Original work published 1996)