Cell surface proteins of Drosophila. I. Changes induced by 20-hydroxyecdysone

Treatment of several Drosophila cell lines with the molting hormone (20-hydroxyecdysone) resulted in biochemical and cellular changes including the morphogenetic process of cell aggregation. Radiolabeling of the cell surface proteins revealed 34 polypeptides that are modulated by the hormone's action. This modulation included both expression of "new" proteins and disappearance of preexisting polypeptides. Whereas most of the hormone-induced proteins were lentil lectin-binding glycoproteins, only one group of disappearing proteins appears to bind lentil lectin. Labeling of the cell surface prior to hormone addition revealed no specific modification of preexisting surface proteins which could account for the protein changes observed with one possible exception. The potential relationship between the modulation in surface proteins and the increase in cell-cell adhesion that occurs during hormone exposure is discussed.