Identification of protein tyrosine phosphatases with specificity for the ligand-activated growth hormone receptor.
Protein tyrosine phosphatases (PTPs) play key roles in switching off tyrosine phosphorylation cascades, such as initiated by cytokine receptors. We have used substrate-trapping mutants of a large set of PTPs to identify members of the PTP family that have substrate specificity for the phosphorylated human GH receptor (GHR) intracellular domain. Among 31 PTPs tested, T cell (TC)-PTP, PTP-beta, PTP1B, stomach cancer-associated PTP 1 (SAP-1), Pyst-2, Meg-2, and PTP-H1 showed specificity for phosphorylated GHR that had been produced by coexpression with a kinase in bacteria. We then used GH-induced, phosphorylated GH receptor, purified from overexpressing mammalian cells, in a Far Western-based approach to test whether these seven PTPs were also capable of recognizing ligand-induced, physiologically phosphorylated GHR. In this assay, only TC-PTP, PTP1B, PTP-H1, and SAP-1 interacted with the mature form of the phosphorylated GHR. In parallel, we show that these PTPs recognize very different subsets of the seven GHR tyrosines that are potentially phosphorylated. Finally, mRNA tissue distribution of these PTPs by RT-PCR analysis and coexpression of the wild-type PTPs to test their ability to dephosphorylate ligand-activated GHR suggest PTP-H1 and PTP1B as potential candidates involved in GHR signaling.
Pasquali
Christian
C
Serono Pharmaceutical Research Institute, 1228 Plan-les-Ouates, Geneva, Switzerland.
Curchod
Marie-Laure
ML
Wälchli
Sébastien
S
Espanel
Xavier
X
Guerrier
Mireille
M
Arigoni
Fabrizio
F
Strous
Ger
G
Hooft van Huijsduijnen
Rob
R
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008969:Molecular Sequence Data; D009928:Organ Specificity; D019000:Phosphotyrosine / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011986:Receptors, Somatotropin / Q000819:agonists* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013379:Substrate Specificity; D014443:Tyrosine / Q000378:metabolism
D008024:Ligands; D011986:Receptors, Somatotropin; D019000:Phosphotyrosine; D014443:Tyrosine; D013006:Growth Hormone; D017027:Protein Tyrosine Phosphatases