A model of activation of the protein tyrosine phosphatase SHP-2 by the human leptin receptor.
Signalling through the leptin receptor has been shown to activate the SH2 domain-containing tyrosine phosphatase SHP-2 through tyrosine phosphorylation. The human leptin receptor contains five tyrosine residues in the cytoplasmic domain that may become phosphorylated. We show here using BIAcore studies, wherein binding of peptides to SHP-2 was detected, that peptides corresponding to sequences containing phosphotyrosines 974 and 986 (LR974P and LR986P, respectively) from the leptin receptor cytoplasmic domain were the only two peptides that bound to the enzyme. Binding of LR974P to SHP-2 was inhibited in a dose-dependent fashion by orthovanadate, whereas binding of LY986P was not, indicating that the enzyme binds to these peptides through different sites. Only the leptin receptor-derived peptide corresponding to tyrosine 974 was dephosphorylated by recombinant purified SHP-2. Time courses of the reaction were complex, and fitted a two exponent rate equation. Preincubation of SHP-2 with LR986P markedly activated the enzyme at early time points and time courses of the activated enzyme fitted a single exponential first order rate equation. We propose that LR974P binds to the active site of SHP-2, whereas LR986P may bind to the N- and C-terminal SH2 domains of SHP-2, thus activating the phosphatase activity. These data support a model in which SHP-2 binds to phosphotyrosine 986 in the activated leptin receptor and is activated to dephosphorylate phosphotyrosine 974, downregulating signalling events emanating from SH2 domain-containing proteins that bind here.
Löthgren
A
A
Pharmacia and Upjohn AB, Stockholm, Sweden.
McCartney
M
M
Rupp Thuresson
E
E
James
S R
SR
D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry / Q000502:physiology*; D020134:Catalytic Domain; D004789:Enzyme Activation; D004926:Escherichia coli; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008956:Models, Chemical; D009447:Neuroblastoma / Q000473:pathology; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000737:chemistry / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation / Q000187:drug effects; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D014638:Vanadates / Q000494:pharmacology; D018909:src Homology Domains
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C515448:LEPR protein, human; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D011993:Recombinant Fusion Proteins; D019000:Phosphotyrosine; D014638:Vanadates; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases