Cloning of a novel, ubiquitously expressed human phosphatidylinositol 3-kinase and identification of its binding site on p85.

• DOI: 10.1128/mcb.13.12.7677
• Publication Date: 2015-10-06T00:37:17Z
• Authors: P Hu; A Mondino; E Y Skolnik; J Schlessinger
• Keywords: 0301 basic medicine; 0303 health sciences; Binding Sites; DNA, Complementary; Base Sequence; Sequence Homology, Amino Acid; Recombinant Fusion Proteins; Molecular Sequence Data; Gene Expression; Saccharomyces cerevisiae; Phosphatidylinositol 3-Kinases; Phosphotransferases (Alcohol Group Acceptor); 03 medical and health sciences; Animals; Humans; Cattle; Amino Acid Sequence; RNA, Messenger; Cloning, Molecular; Sequence Tagged Sites

Phosphatidylinositol 3-kinase (PI 3-kinase) has been implicated as a participant in signaling pathways regulating cell growth by virtue of its activation in response to various mitogenic stimuli. Here we describe the cloning of a novel and ubiquitously expressed human PI 3-kinase. The 4.8-kb cDNA encodes a putative translation product of 1,070 amino acids which is 42% identical to bovine PI 3-kinase and 28% identical to Vps34, a Saccharomyces cerevisiae PI 3-kinase involved in vacuolar protein sorting. Human PI 3-kinase is also similar to Tor2, a yeast protein required for cell cycle progression. Northern (RNA) analysis demonstrated expression of human PI 3-kinase in all tissues and cell lines tested. Protein synthesized from an epitope-tagged cDNA had intrinsic PI 3-kinase activity and associated with the adaptor 85-kDa subunit of PI 3-kinase (p85) in intact cells, as did endogenous human PI 3-kinase. Coprecipitation assays showed that a 187-amino-acid domain between the two src homology 2 domains of p85 mediates interaction with PI 3-kinase in vitro and in intact cells. These results demonstrate the existence of different PI 3-kinase isoforms and define a family of genes encoding distinct PI 3-kinase catalytic subunits that can associate with p85.