Structural highlights
Function
PTPA_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]
Publication Abstract from PubMed
Abstract Protein phosphatase 2A (PP2A) is a highly abundant heterotrimeric Ser/Thr phosphatase involved in the regulation of a variety of signaling pathways. The PP2A phosphatase activator (PTPA) is an ATP-dependent activation chaperone, which plays a key role in the biogenesis of active PP2A. The C-terminal tail of the catalytic subunit of PP2A is highly conserved and can undergo a number of posttranslational modifications that serve to regulate the function of PP2A. Here we have studied structurally the interaction of PTPA with the conserved C-terminal tail of the catalytic subunit carrying different posttranslational modifications. We have identified an additional interaction site for the invariant C-terminal tail of the catalytic subunit on PTPA, which can be modulated via posttranslational modifications. We show that phosphorylation of Tyr307PP2A-C or carboxymethylation of Leu309PP2A-C abrogates or diminishes binding of the C-terminal tail, whereas phosphorylation of Thr304PP2A-C is of no consequence. We suggest that the invariant C-terminal residues of the catalytic subunit can act as affinity enhancer for different PP2A interaction partners, including PTPA, and a different 'code' of posttranslational modifications can favour interactions to one subunit over others.
Structural basis for PTPA interaction with the invariant C-terminal tail of PP2A.,Low C, Quistgaard EM, Kovermann M, Anandapadamanaban M, Balbach J, Nordlund P Biol Chem. 2014 Jul 1;395(7-8):881-9. doi: 10.1515/hsz-2014-0106. PMID:25003389[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Azam S, Drobetsky E, Ramotar D. Overexpression of the cis/trans isomerase PTPA triggers caspase 3-dependent apoptosis. Apoptosis. 2007 Jul;12(7):1243-55. PMID:17333320 doi:http://dx.doi.org/10.1007/s10495-006-0050-8
- ↑ Chao Y, Xing Y, Chen Y, Xu Y, Lin Z, Li Z, Jeffrey PD, Stock JB, Shi Y. Structure and mechanism of the phosphotyrosyl phosphatase activator. Mol Cell. 2006 Aug;23(4):535-46. PMID:16916641 doi:http://dx.doi.org/10.1016/j.molcel.2006.07.027
- ↑ Low C, Quistgaard EM, Kovermann M, Anandapadamanaban M, Balbach J, Nordlund P. Structural basis for PTPA interaction with the invariant C-terminal tail of PP2A. Biol Chem. 2014 Jul 1;395(7-8):881-9. doi: 10.1515/hsz-2014-0106. PMID:25003389 doi:http://dx.doi.org/10.1515/hsz-2014-0106
