A NOVEL KH-DOMAIN PROTEIN MEDIATES CELL-ADHESION PROCESSES IN DROSOPHILA

Adhesion of cells to one another and to extracellular matrices has maj or roles in morphogenetic processes during development. One important family of cell adhesion receptors are the integrins, which in Drosophi la have crucial functions in at least two adhesion-mediated developmen tal events: embryonic muscle attachment and adhesion of the wing epith elia. We have cloned and characterized a gene (struthio) that is expre ssed in embryonic mesodermal and muscle cells, including cardioblasts, and epidermal muscle attachment sites in a pattern that is reminiscen t of the expression pattern of the PS integrins. Maternal and zygotic transcripts are produced by this gene and encode similar proteins with two alternative carboxy tails. Both proteins contain identical KH dom ains, a protein sequence motif that is found in numerous proteins that interact with RNA. The struthio protein is highly homologous in a reg ion including the KH domain to the mouse quaking and C. elegans gld-1 proteins, two developmentally important genes. Somatic homozygous clon es of an embryonic lethal mutation in this gene (stru(1A122)) cause wi ng blisters and night impairment, phenotypes which are associated with PS integrin subunit mutations. Thus, the struthio gene encodes a puta tive RNA-binding protein that appears to regulate some aspects of Dros ophila integrin functioning. (C) 1997 Academic Press.