EXPRESSION OF THE MAJOR TYROSYL PHOSPHOPROTEIN OF 54-KDA IN THE INTEGUMENT OF THE MEDFLY CERATITIS-CAPITATA

Expression of a 54 kDa tyrosyl phosphorylated protein in epidermal cel ls during the third instar larval stage was followed. It was demonstra ted that the 54 kDa protein moiety and its phosphorylated counterpart follow the same developmental profile. The system seems to be regulate d only at the onset of the second moult, by an initial signal which re gulates both the synthesis and phosphorylation of a 54 kDa protein. Th e continuous presence this protein in epidermal cells during the third instar stage, as well as during apolysis and histolysis, suggests tha t it might participate in cell activities taking place during this dev elopmental period. However, the 54 kDa protein could no be involved in specific epidermal cell activities such as histolysis, melanization a nd sclerotization, since these activities occur only at specific times during the third instar stage.