2ixm
Structure of human PTPA
Structural highlights
FunctionPTPA_HUMAN PPIases accelerate the folding of proteins. It catalyzes the cis-trans isomerization of proline imidic peptide bonds in oligopeptides. Acts as a regulatory subunit for serine/threonine-protein phosphatase 2A (PP2A) modulating its activity or substrate specificity, probably by inducing a conformational change in the catalytic subunit, a proposed direct target of the PPIase. Can reactivate inactive phosphatase PP2A-phosphatase methylesterase complexes (PP2A(i)) in presence of ATP and Mg(2+) (By similarity). Reversibly stimulates the variable phosphotyrosyl phosphatase activity of PP2A core heterodimer PP2A(D) in presence of ATP and Mg(2+) (in vitro). The phosphotyrosyl phosphatase activity is dependent of an ATPase activity of the PP2A(D):PPP2R4 complex. Is involved in apoptosis; the function appears to be independent from PP2A.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedPTPA, an essential and specific activator of protein phosphatase 2A (PP2A), functions as a peptidyl prolyl isomerase (PPIase). We present here the crystal structures of human PTPA and of the two yeast orthologs (Ypa1 and Ypa2), revealing an all alpha-helical protein fold that is radically different from other PPIases. The protein is organized into two domains separated by a groove lined by highly conserved residues. To understand the molecular mechanism of PTPA activity, Ypa1 was cocrystallized with a proline-containing PPIase peptide substrate. In the complex, the peptide binds at the interface of a peptide-induced dimer interface. Conserved residues of the interdomain groove contribute to the peptide binding site and dimer interface. Structure-guided mutational studies showed that in vivo PTPA activity is influenced by mutations on the surface of the peptide binding pocket, the same mutations that also influenced the in vitro activation of PP2Ai and PPIase activity. Crystal structure of the PP2A phosphatase activator: implications for its PP2A-specific PPIase activity.,Leulliot N, Vicentini G, Jordens J, Quevillon-Cheruel S, Schiltz M, Barford D, van Tilbeurgh H, Goris J Mol Cell. 2006 Aug 4;23(3):413-24. PMID:16885030[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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