ROLE OF THE PS INTEGRINS IN DROSOPHILA DEVELOPMENT

The PS1 and PS2 integrins of Drosophila are heterodimers of alpha pS1 beta pS and alpha pS2 beta pS subunits, respectively, with very strong structural similarity to vertebrate integrins. Cell transfection expe riments indicate that the PS integrins are receptors for extracellular matrix components and are functionally analogous to vertebrate integr ins. Matrix ligands from Drosophila tissues have been identified for P S1 and PS2 integrins, using transformed cells and a cell-spreading ass ay. Mutations in ail three subunit genes have been identified, and the phenotypes of mutants indicate that PS integrins are required for the proper morphogenesis of a number of embryonic tissues. Using methods to produce genetic mosaics and transformation of integrin transgenes i nto whole animals. integrin functions in adult morphogenesis also have been examined. In the pupal wing, integrins are critically required t o maintain the connection between dorsal and ventral epithelia, and re cent results suggest that in early pupal development, the integrins ar e acting as specific receptors, as opposed to a non-specific cell-matr ix glue.