Phosphorylation of spore coat proteins of Dictyostelium discoideum

Abstract

Phosphorylation of cellular proteins was studied during development of Dictyostelium discoideum. In the second half of the developmental cycle, two heavily phosphorylated proteins were observed together with a limited number of minor phosphorylated proteins. The electrophoretic mobility of these two phosphoproteins corresponded to two of the major spore coat glycoproteins, with apparent molecular weights of 103 000 and 80 000. They were found to be externalized and associated with the spore coat during spore formation. Phosphoserine was the predominant phosphoamino acid in both cases. These two phosphoproteins thus serve as excellent markers for the differentiation of prespore cells in D. discoideum.