Calcium/calmodulin-dependent phosphorylation of vimentin in rat sertoli cells.

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Abstract
Ca2+-dependent protein phosphorylation and the role of calmodulin in this process was investigated in subcellular fractions of primary cultures of rat Sertoli cells. Significant Ca2+/calmodulin-dependent protein phosphorylation in Sertoli cells was restricted to the cytosol fraction. The calmodulin dependence of these effects was confirmed by using the calmodulin inhibitor trifluoperazine. One of the Ca2+/calomodulin-dependent phosphoproteins was identified as the intermediate filament protein vimentin, based on the following criteria: migration pattern in 2-dimensional polyacrylamide gels, Ca2+/calmodulin-dependent phosphorylation of a 58-kilodalton protein present in detergent-insoluble intermediate filament protein extract of Sertoli cells and peptide mapping of the phosphoprotein. These data support a role for Ca2+/calmodulin-dependent protein phosphorylation in the modulation of Sertoli cell cytoskeletal components.