Cmk2 is a homolog of mammalian calcium/calmodulin-dependent protein kinase II (CaMKII), and functions as a negative regulator of calcium signaling in yeast cells. Transcription of CMK2 gene is controlled by the zinc finger transcription factor Crz1 via a CDRE motif in the promoter. In this study, we have characterized the protein expression and phosphorylation of Cmk2. Purified Cmk2 proteins from yeast cells undergo autophosphorylation. Two forms of Cmk2 proteins, the slow-migrating (SM-Cmk2) and the fast-migrating (FM-Cmk2), were detected in response of yeast cells to calcium stress. In the absence of calcium stress, Cmk2 appears to be mainly in the form of SM-Cmk2. Deletion of CNB1 delays the calcium-induction of both forms, but only reduces the level of the calcium-induced FM-Cmk2. An extracellular calcium concentration of 200 mM results in maximal induction of both forms of Cmk2. Therefore, in addition to calcium/calcineurin signaling, expression of Cmk2 protein is controlled by additional factor(s). Furthermore, our mutational analysis indicates that the K76 residue of Cmk2 is required for the calcium-induction and steady-state expression levels of both FM-Cmk2 and SM-Cmk2. The S317 residue, the counterpart of the O-linked glycosylation site S279 in mammalian CaMKII, is also responsible for the calcium-induction of SM-Cmk2.

• PMID: 41290071
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Journal Article

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Jiang L, Wei L, Gu Y, Jiang P, Snyder N, Liao X, Mo Y, Pan L, Wei C, Cunningham KW

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