ISOLATION AND CHARACTERIZATION OF THE DROPIK57 GENE ENCODING A NEW REGULATORY SUBUNIT OF PHOSPHATIDYLINOSITOL 3-KINASE FROM DROSOPHILA-MELANOGASTER

Mammalian phosphatidylinositol 3-kinase (PI 3-kinase) plays an importa nt role in the regulation of various cellular, receptor tyrosine kinas e-mediated processes, such as mitogenesis and transformation. PI 3-kin ase is composed of a 110-kDa catalytic subunit and a regulatory subuni t of 85 kDa or 55 kDa. We have cloned a gene for a regulatory subunit from Drosophila melanogaster, named droPIK57, from head-specific cDNA libraries. The droPIK57 gene encodes a protein containing two SH2 doma ins with significant sequence homology to those in p85 and p55. Like t he p55 subunits, DroPIK57 is missing the SH3 domain and the bcr homolo gy region of the p85 subunit. The short N-terminus as well as the C-te rminus of the DroPIK57 protein show no identity to the known PI 3-kina se subunits, suggesting that it is a new member in the family of regul atory subunits. In-situ hybridization and Northern blot analysis indic ate a widespread function of this gene during embryogenesis and in the CNS. (C) 1997 Elsevier Science B.V.