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The role of the C-terminal domain of protein tyrosine phosphatase-1B in phosphatase activity and substrate binding.

Picha, Kristen and Patel, Smita and Mandiyan, Sreekala and Koehn, James and Wennogle, Lawrence (2007) The role of the C-terminal domain of protein tyrosine phosphatase-1B in phosphatase activity and substrate binding. The Journal of Biological Chemistry, 282 (5). pp. 2911-2917. ISSN 0021-9258

Abstract

Protein tyrosine phosphatase 1B (PTP-1B) has been implicated in the regulation of the insulin receptor. Dephosphorylation of the insulin receptor results in decreased insulin signaling and thus decreased glucose uptake. PTP-1B-/- mice have increased insulin sensitivity and are resistant to weight gain when fed a high fat diet, validating PTP-1B as a potential target for the treatment of type 2 diabetes. Many groups throughout the world have been searching for selective inhibitors for PTP-1B, and most of them target inhibitors to PTP-1B-(1-298), the N-terminal catalytic domain of the enzyme. However, the C-terminal domain is quite large and could influence the activity of the enzyme. Using two constructs of PTP-1B and a phosphopeptide as substrate, steady state assays showed that the presence of the C-terminal domain decreased both the Km and the k(cat) 2-fold. Pre-steady state kinetic experiments showed that the presence of the C-terminal domain improved the affinity of the enzyme for a phosphopeptide 2-fold, primarily because the off-rate was slower. This suggests that the C-terminal domain of PTP-1B may contact the phosphopeptide in some manner, allowing it to remain at the active site longer. This could be useful when screening libraries of compounds for inhibitors of PTP-1B. A compound that is able to make contacts with the C-terminal domain of PTP-1B would not only have a modest improvement in affinity but may also provide for specificity over other phosphatases.

Item Type: Article
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Additional Information: author can archive post-print (ie final draft post-refereeing); Publisher's version/PDF cannot be used
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Date Deposited: 14 Dec 2009 13:58
Last Modified: 31 Jan 2013 01:13
URI: https://oak.novartis.com/id/eprint/558

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