1,25-Dihydroxyvitamin D effects in the kidney: induction of calmodulin binding proteins

A marked induction of 125I-calmodulin binding proteins (185kDa and 115kDa) occurred in the rat kidney in response to treatment with 1,25-dihydroxyvitamin D3 (100 ng/day s.c. x 7d). These 125I-calmodulin binding proteins, measured by the gel overlay procedure, exhibited calcium dependence and were abolished in the presence of excess unlabelled calmodulin. The response was tissue specific: there was no change in 125I-calmodulin binding in rat testis, heart, and brain and only a modest elevation of binding to one calmodulin binding protein in the intestinal mucosa. These results are particularly important in suggesting that the calmodulin signal transduction mechanism may, via changes in its acceptor proteins, participate in mediating some biological effects of 1,25-dihydroxyvitamin D3.