Characterization of two 85 kd proteins that associate with receptor tyrosine kinases, middle-T/pp60c-src complexes, and PI3-kinase.
Affinity-purified bovine brain phosphatidylinositol 3-kinase (PI3-kinase) contains two major proteins of 85 and 110 kd. Amino acid sequence analysis and cDNA cloning reveals two related 85 kd proteins (p85 alpha and p85 beta), which both contain one SH3 and two SH2 regions (src homology regions). When expressed, these 85 kd proteins bind to and are substrates for tyrosine-phosphorylated receptor kinases and the polyoma virus middle-T antigen/pp60c-src complex, but lack PI3-kinase activity. However, an antiserum raised against p85 beta immunoprecipitates PI3-kinase activity. The active PI3-kinase complex containing p85 alpha or p85 beta and the 110 kd protein binds to PDGF but not EGF receptors. p85 alpha and p85 beta may mediate specific PI3-kinase interactions with a subset of tyrosine kinases.
Otsu
M
M
Ludwig Institute for Cancer Research, London, England.
Hiles
I
I
Gout
I
I
Fry
M J
MJ
Ruiz-Larrea
F
F
Panayotou
G
G
Thompson
A
A
Dhand
R
R
Hsuan
J
J
Totty
N
N
D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism*; D016367:Baculoviridae / Q000235:genetics; D001483:Base Sequence; D015139:Blotting, Southern; D001921:Brain / Q000201:enzymology; D002417:Cattle; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA; D015723:Gene Library; D006801:Humans; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases; D010770:Phosphotransferases / Q000378:metabolism*; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D051562:Proto-Oncogene Proteins c-bcr; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D013552:Swine
D000952:Antigens, Polyomavirus Transforming; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D004247:DNA; D010770:Phosphotransferases; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D016392:Proto-Oncogene Proteins pp60(c-src); C496613:BCR protein, human; D051562:Proto-Oncogene Proteins c-bcr