The Effect of Dephosphorylation on the Properties of a Helix‐Destabilizing Protein from Meiotic Cells and Its Partial Reversal by a Protein Kinase

Abstract

Properties of the helix‐destabilizing protein from Lilium meiotic cells, ‘R‐protein’, have been examined after treating it either with alkaline phosphatase or with two types of protein kinase. Dephosphorylation with the phosphatase increases binding capacity for single‐strand DNA, but abolishes specificity of binding. Dephosphorylated R‐protein binds equally to single and double‐strand DNA. The capacity to facilitate denaturation or renaturation of DNA is also abolished by the treatment, but cooperativity characteristics are unaffected. The consequences of protein kinase treatment of native or dephosphorylated R‐protein depend upon the origin of the kinase. Heterologous cyclic‐AMP‐dependent protein kinase cannot reverse the effects of dephosphorylation. However, it abolishes the binding affinity of either native or dephosphorylated R‐protein for DNA. A protein kinase isolated from meiotic cells has no effect on the native protein, but it does restore all native properties tested to the dephosphorylated form after phosphorylating approximately two residues/molecule of protein.