Phosphorylation of threonine residues on cloned fragments of the Dictyostelium myosin heavy chain |
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Authors: | G Wagle A Noegel J Scheel G Gerisch |
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Affiliation: | Max-Planck-Institut für Biochemie, Martinsried, FRG. |
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Abstract: | A tail fragment of Dictyostelium discoideum myosin has been cloned and expressed as a fusion protein with the N-terminal region of MS-2 polymerase. The cloned fragment was phosphorylated with myosin heavy chain kinase II from aggregation-competent D. discoideum cells that specifically phosphorylate threonine residues on the myosin tail. Phosphopeptide maps showed the same site specificity of phosphorylation with the fusion protein as a substrate as with native myosin. An improved assay for the kinase was developed in which the fusion protein is precipitated with a monoclonal antibody that inhibits polymerization of the myosin tails without preventing their phosphorylation. Sites of phosphorylation were tentatively localized to a sequence in the C-terminal region of the heavy chain where four threonine residues are found. |
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