Identification of Phosphorylated 422(aP2) Protein as pp15, the 15-kilodalton Target of the Insulin Receptor Tyrosine Kinase in 3T3-L1 Adipocytes

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 85; no. 23; pp. 8835 - 8839
• Main Authors: Hresko, Richard C., Bernier, Michel, Hoffman, Robert D., Flores-Riveros, Jaime R., Liao, Kan, Laird, Don M., Lane, M. Daniel
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.12.1988; National Acad Sciences
• Subjects: Adipocytes; Adipose Tissue - enzymology; Amino Acid Sequence; Amino acids; Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Carrier Proteins - isolation & purification; Carrier Proteins - metabolism; Cells, Cultured; Electrophoresis; Fatty Acid-Binding Protein 7; Fatty Acid-Binding Proteins; Fundamental and applied biological sciences. Psychology; Gels; Insulin; Mice; Miscellaneous; Molecular Sequence Data; Molecular Weight; Neoplasm Proteins; Nerve Tissue Proteins; Peptide Fragments - analysis; Phosphates - metabolism; Phosphopeptides - analysis; Phosphorylation; protein-tyrosine kinase; Protein-Tyrosine Kinases - metabolism; Proteins; Quaternary ammonium compounds; Receptor, Insulin; Receptors; Substrate Specificity; Sulfates; Vanadates
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.85.23.8835

[32P]pp15, the [32P]phosphorylated form of a specific cytosolic substrate of the insulin receptor tyrosine kinase, was purified to homogeneity from mouse 3T3-L1 adipocytes incubated with 32Pi. Evidence presented here and previously indicates that pp15 contains a single phosphotyrosine residue. Alkylated [32P]pp15 was subjected to limited digestion with trypsin, after which three incompletely digested tryptic [32P]phosphopeptides were purified for analysis. Amino acid and radiochemical sequence analysis of the [32P]phosphopeptides revealed that pp15 is the phosphorylation product of 422(aP2) protein, a 15-kDa adipocyte protein previously sequenced in this laboratory from the corresponding cDNA.