Expression and characterization of wild type, truncated, and mutant forms of the intracellular region of the receptor-like protein tyrosine phosphatase HPTP beta.

Wang, Y; Pallen, Catherine J.

doi:10.1016/s0021-9258(18)42058-3

Cited by 26 publications

(2 citation statements)

References 48 publications

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“…Interestingly, the Kmax values obtained for APTP1C and PTP 1C for phosphotyrosyl IPRs fall within the range of values published for LAR and CD45 using phosphotyrosyl IRPs (Tonks et al, 1990;Hyeongjin et al, 1992;Lee et al, 1992). In addition, the Km values found here for PTP 1C were as low as the lowest reported Km values and the k^/Km values were at least 5-fold higher than the highest reported kclx/Km values for a number of different PTPs with various protein and peptide substrates (Tonks et al, 1988(Tonks et al, , 1990Daum et al, 1991;Hyeongjin et al, 1992;Lee et al, 1992;Wang & Pallen, 1992;Zhang et al, 1992).…”

Section: Discussionsupporting

confidence: 85%

Inhibition of the activity of protein tyrosine phosphatase 1C by its SH2 domains

Townley¹,

Shen²,

Banville³

et al. 1993

Biochemistry

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Full-length protein tyrosine phosphatase 1C (PTP1C), the catalytic domain of PTP1C (delta PTP1C), and the N-terminal SH2 domain truncated PTP1C (delta NPTP1C) were overexpressed in Escherichia coli and purified to near homogeneity. Various phosphorylated states of the synthetic phosphotyrosyl peptide TRDIYETDYYRK (IRP), corresponding to the major insulin receptor autophosphorylation sites, were used as substrates for the PTPs. There was no indication for selective dephosphorylation of any of the three phosphotyrosyl residues from the triphosphotyrosyl IRP. Kinetic studies were carried out using all seven different phosphotyrosyl IRPs. Saturation kinetics were observed for PTP1C using the triphosphotyrosyl IRP only. In contrast, for delta PTP1C, saturation was achieved for all seven phosphotyrosyl IRPs. The best substrate for delta PTP1C was the triphosphotyrosyl IRP possessing a Km of approximately 1.6 microM, about 3-4-fold lower than either the mono- or diphosphotyrosyl IRPs. However, in contrast to delta PTP1C, PTP1C had a 22-fold lower affinity for triphosphotyrosyl IRP. Furthermore, deletion of a single N-terminal SH2 domain increased the affinity of the enzyme for the triphosphotyrosyl IRP to a value similar to that obtained with delta PTP1C. The pH optima for all three enzyme constructs were very similar and could not account for the observed change in substrate affinity between the three enzymes. These results suggest that the SH2 domain of PTP1C exerts an inhibitory effect on its PTP activity.

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Section: Discussionsupporting

confidence: 85%

Inhibition of the activity of protein tyrosine phosphatase 1C by its SH2 domains

Townley¹,

Shen²,

Banville³

et al. 1993

Biochemistry

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“…Moreover, we have previously shown that treatment of BEAS cells with a V-containing metallic mixture rapidly induces a persistent accumulation of protein Tyr phosphates through a mechanism that involves protein Tyr phosphatase inhibition (50). Similarly, trivalent As reportedly activates JNK and P38 in HeLa cells by inhibiting a dual-specificity Thr/Tyr phosphatase (5), and Zn has been shown to inhibit the receptor Tyr phosphatase HPTP beta (62). Thus the fact that the metals As, V, and Zn, which we report as the most potent activators of MAPKs, are known phosphatase inhibitors suggests that disruption of Tyr phosphate and, possibly, Ser/Thr phosphate homeostasis is a pivotal initiating event in metal-induced activation of MAPKs.…”

Section: Discussionmentioning

confidence: 99%

Activation of MAPKs in human bronchial epithelial cells exposed to metals

Samet

Graves

Quay

et al. 1998

American Journal of Physiology-Lung Cellular and Molecular Phys

198

168

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We have previously shown that in vitro exposure to metallic compounds enhances expression of interleukin (IL)-6, IL-8, and tumor necrosis factor-α in human bronchial epithelial cells. To characterize signaling pathways involved in metal-induced expression of inflammatory mediators and to identify metals that activate them, we studied the effects of As, Cr, Cu, Fe, Ni, V, and Zn on the mitogen-activated protein kinases (MAPK) extracellular receptor kinase (ERK), c-Jun NH2-terminal kinase (JNK), and P38 in BEAS cells. Noncytotoxic concentrations of As, V, and Zn induced a rapid phosphorylation of MAPK in BEAS cells. Activity assays confirmed marked activation of ERK, JNK, and P38 in BEAS cells exposed to As, V, and Zn. Cr and Cu exposure resulted in a relatively small activation of MAPK, whereas Fe and Ni did not activate MAPK under these conditions. Similarly, the transcription factors c-Jun and ATF-2, substrates of JNK and P38, respectively, were markedly phosphorylated in BEAS cells treated with As, Cr, Cu, V, and Zn. The same acute exposure to As, V, or Zn that activated MAPK was sufficient to induce a subsequent increase in IL-8 protein expression in BEAS cells. These data suggest that MAPK may mediate metal-induced expression of inflammatory proteins in human bronchial epithelial cells.

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Protein Tyrosine Phosphatases: Mechanism of Catalysis and Substrate Specificity

Zhang¹,

Dixon²

1994

Advances in Enzymology - And Related Areas of Molecular Biology

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Expression and characterization of wild type, truncated, and mutant forms of the intracellular region of the receptor-like protein tyrosine phosphatase HPTP beta.

Cited by 26 publications

References 48 publications

Inhibition of the activity of protein tyrosine phosphatase 1C by its SH2 domains

Inhibition of the activity of protein tyrosine phosphatase 1C by its SH2 domains

Activation of MAPKs in human bronchial epithelial cells exposed to metals

Protein Tyrosine Phosphatases: Mechanism of Catalysis and Substrate Specificity

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