Fig. 1.

Conditions that increase pY-actin in Dictyostelium. (A) Relative amounts of pY-actin in vegetative (V) and starved (S) amoebae and fruiting bodies (F) by immunoblotting with anti-pY antibody. (B) Increase of pY-actin in cells exposed to CdCl₂, heat, NaN₃, or PAO. (C) Increase in pY-actin with days in culture. (D) Specificity of anti-phosphotyrosine antibody. Immunoblotting of phosphorylated actin is blocked by 1 mM pY but not by 1 mM pS or 1 mM pT. CB, Coomassie blue; pY, phosphotyrosine; pS, phosphoserine; pT, phosphothreonine.