Identification of phosphorylated 422(aP2) protein as pp15, the 15-kilodalton target of the insulin receptor tyrosine kinase in 3T3-L1 adipocytes.
[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.
Hresko
R C
RC
Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Bernier
M
M
Hoffman
R D
RD
Flores-Riveros
J R
JR
Liao
K
K
Laird
D M
DM
Lane
M D
MD
D000273:Adipose Tissue / Q000201:enzymology*; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000302:isolation & purification* / Q000378:metabolism; D002478:Cells, Cultured; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments / Q000032:analysis; D010710:Phosphates / Q000378:metabolism; D010748:Phosphopeptides / Q000032:analysis; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011972:Receptor, Insulin; D013379:Substrate Specificity
D002352:Carrier Proteins; C082667:Fabp5 protein, mouse; C086936:Fabp7 protein, mouse; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D010710:Phosphates; D010748:Phosphopeptides; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin