Linked Life Data

10978177

Source:http://linkedlifedata.com/resource/pubmed/id/10978177

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
35
pubmed:dateCreated
2000-9-28
pubmed:abstractText
Gab-1 (Grb2-associated binder-1), which appears to play a central role in cellular growth response, transformation, and apoptosis, is a member of the insulin receptor substrate (IRS) family. IRS proteins act downstream in the signaling pathways of different receptor tyrosine kinases, including the insulin receptor (IR). In this paper, we characterize the phosphorylation of recombinant human Gab-1 (hGab-1) by IR in vitro. Kinetic phosphorylation data revealed that hGab-1 is a high affinity substrate for the IR (K(M): 12.0 microM for native IR vs 23.3 microM for recombinant IR). To elucidate the IR-specific phosphorylation pattern of hGab-1, we used phosphopeptide mapping by two-dimensional HPLC analysis. Phosphorylated tyrosine residues were subsequently identified by sequencing the separated phosphopeptides by matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) and Edman degradation. Our results demonstrate that hGab-1 was phosphorylated by IR at eight tyrosine residues (Y242, Y285, Y373, Y447, Y472, Y619, Y657, and Y689). Seventy-five percent of the identified radioactivity was incorporated into tyrosine residues Y447, Y472, and Y619 exhibiting features (NYVPM motif) of potential binding sites for the regulatory subunit (p85) of phosphatidylinositol (PI)-3 kinase. Accordingly, pull down assays with human HepG2 cell lysates showed that IR-specific phosphorylation of wild-type hGab-1 strongly enhanced PI-3 kinase binding. This is still the case when a single tyrosine residue in the NYVPM motif was mutated to phenylalanine. In contrast, phosphorylation-dependent binding of PI-3 kinase was completely abolished by changing a second tyrosine residue in a NYVPM motif independent from its location. Recently, we identified a similar cohort of tyrosine phosphorylation sites for the epidermal growth factor receptor (EGFR) with a predominant phosphorylation of tyrosine residue Y657 and binding of Syp [Lehr, S. et al. (1999) Biochemistry 38, 151-159]. These differences in the phosphorylation pattern of hGab-1 may contribute to signaling specificity by different tyrosine kinase receptors engaging distinct SH2 signaling molecules.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
5
pubmed:volume
39
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10898-907
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed-meshheading:10978177-Adaptor Proteins, Signal Transducing, pubmed-meshheading:10978177-Amino Acid Sequence, pubmed-meshheading:10978177-Binding Sites, pubmed-meshheading:10978177-Humans, pubmed-meshheading:10978177-Insulin Receptor Substrate Proteins, pubmed-meshheading:10978177-Molecular Sequence Data, pubmed-meshheading:10978177-Mutagenesis, Site-Directed, pubmed-meshheading:10978177-Phosphatidylinositol 3-Kinases, pubmed-meshheading:10978177-Phosphoproteins, pubmed-meshheading:10978177-Phosphorylation, pubmed-meshheading:10978177-Receptor, Insulin, pubmed-meshheading:10978177-Recombinant Fusion Proteins, pubmed-meshheading:10978177-Spectrometry, Mass, Matrix-Assisted Laser..., pubmed-meshheading:10978177-Substrate Specificity, pubmed-meshheading:10978177-Tumor Cells, Cultured, pubmed-meshheading:10978177-Tyrosine
pubmed:year
2000
pubmed:articleTitle
Identification of major tyrosine phosphorylation sites in the human insulin receptor substrate Gab-1 by insulin receptor kinase in vitro.
pubmed:affiliation
Klinik II und Poliklinik für Innere Medizin at the Centre of Molecular Medicine of Cologne, Universität zu Köln, Cologne, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't