1c0e
From Proteopedia
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ACTIVE SITE S19A MUTANT OF BOVINE HEART PHOSPHOTYROSYL PHOSPHATASE
Overview
The bovine protein tyrosine phosphatase (BPTP) is a member of the class of, low-molecular weight protein tyrosine phosphatases (PTPases) found to be, ubiquitous in mammalian cells. The catalytic site of BPTP contains a, CX(5)R(S/T) phosphate-binding motif or P-loop (residues 12-19) which is, the signature sequence for all PTPases. Ser19, the final residue of the, P-loop motif, interacts with the catalytic Cys12 and participates in, stabilizing the conformation of the active site through interactions with, Asn15, also in the P-loop. Mutations at Ser19 result in an enzyme with, altered kinetic properties with changes in the pK(a) of the neighboring, His72. The X-ray structure of the S19A mutant enzyme shows that the, general conformation of the P-loop is preserved. However, changes in the, loop containing His72 result in a displacement of the His72 side chain, that may explain the shift in the pK(a). In addition, it was found that in, the crystal, the protein forms a dimer in which Tyr131 and Tyr132 from one, monomer insert into the active site of the other monomer, suggesting a, dual-tyrosine motif on target sites for this enzyme. Since the activity of, this PTPase is reportedly regulated by phosphorylation at Tyr131 and, Tyr132, the structure of this dimer may provide a model of a, self-regulation mechanism for the low-molecular weight PTPases.
About this Structure
1C0E is a Single protein structure of sequence from Bos taurus with PO4 as ligand. Active as Acid phosphatase, with EC number 3.1.3.2 Full crystallographic information is available from OCA.
Reference
The structure of the bovine protein tyrosine phosphatase dimer reveals a potential self-regulation mechanism., Tabernero L, Evans BN, Tishmack PA, Van Etten RL, Stauffacher CV, Biochemistry. 1999 Sep 7;38(36):11651-8. PMID:10512620
Page seeded by OCA on Tue Nov 20 12:03:45 2007
