[Phosphorylation of proteins and phosphoinositides in the axoneme of the bovine rod outer segments. The effect of structural factor].

The protein composition of microtubular structures of bovine retinal rod axoneme and phosphorylation of its proteins were studied. The axoneme was shown to consist of proteins of 25, 43, 51, 112, 145 and 240 kDa molecular mass. It was demonstrated that 32P is mainly incorporated into the 25, 43 and 51 kDa proteins. cGMP was found to enhance 32P. Incorporation into these proteins. In the presence of Ca(2+)-calmodulin the phosphorylation of the 43 and 51 kDa proteins was increased. The phosphoinositides were shown to be phosphorylated in axoneme. Phosphatidylinositol 4-monophosphate was found to be a principal substrate for phosphatidylinositol kinases to form phosphatidylinositol 4,5-bisphosphate. Ca2+, neomycin and colchicine inhibited 32P incorporation into phosphatidylinositol 4,5-bisphosphate indicating the dependence of phosphatidylinositol 4-monophosphate phosphorylation on structural state of axoneme. Phosphatidylinositol was found to diminish the axoneme ability for the polymerization of microtubules. Data was showed that kinases responsible for protein and phosphoinositides phosphorylation were tightly bound to axoneme structures.