Ca2+/calmodulin-binding proteins in yeast. Catabolite repression and induction by carbon sources

Abstract

Soluble calmodulin-binding proteins from Saccharomyces carlsbergensis were analyzed in cells grown on glucose, maltose and galactose as carbon source. A large number of polypeptide chains showed affinity for calmodulin by affinity chromatography and overlay techniques. Amongst these, polypeptides of 115, 67 and 45 kDa were only detected during the second exponential phase of growth on glucose or non-fermentative carbon sources, suggesting that they might be subjected to catabolite repression. Polypeptides of 195 and 22 kDa were only observed in cells grown on maltose, whereas 88 kDa polypeptide was only observed in galactose-grown cells. Among the calmodulin-binding polypeptides, eight were phosphorylated in a Ca2+/calmodulin-dependent manner (220, 200, 175, 100, 62, 55, 31 and 16 kDa). Ca2+/calmodulin dependent [γ-32P] incorporation was dramatically decreased in yeast cells submitted to a heat treatment.