Human Mitogen-activated Protein Kinase CSBP1, but Not CSBP2, Complements a hog1 Deletion in Yeast

• Published in: The Journal of biological chemistry Vol. 270; no. 49; pp. 29043 - 29046
• Main Authors: Kumar, S, McLaughlin, M M, McDonnell, P C, Lee, J C, Livi, G P, Young, P R
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 08.12.1995
• Subjects: Base Sequence; Calcium-Calmodulin-Dependent Protein Kinases - chemistry; Calcium-Calmodulin-Dependent Protein Kinases - physiology; Enzyme Activation; Humans; Mitogen-Activated Protein Kinases; Molecular Sequence Data; Mutation; Phenotype; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.49.29043

CSBP1 and CSBP2 are human homologues of the Saccharomyces cerevisiae Hog1 mitogen-activated protein kinase which is required for growth in high osmolarity media. Expression of CSBP1, but not CSBP2, complemented a hog1 Δ phenotype. A CSBP2 mutant (A34V) that complements hog1 Δ was isolated and found to have 3-fold lower kinase activity than the wild-type CSBP2. Further analysis revealed that both the kinase activity and tyrosine phosphorylation of CSBP1 and CSBP2 (A34V) is regulated by salt. In contrast, wild-type CSBP2 is constitutively active but dependent on the upstream kinase, Pbs2. Mutagenesis studies showed that reduction or elimination of CSBP2 kinase activity restores salt responsiveness as measured by tyrosine phosphorylation suggesting that too high a level of kinase activity can result in desensitization of the host cell and inability to grow in high salt.