Regulation of PTEN Activity by Its Carboxyl-terminal Autoinhibitory Domain

The regulation of PTEN intrinsic biochemical properties has not been fully elucidated. In this report, we investigated the role of the PTEN carboxyl-terminal tail domain in regulating its membrane targeting and catalytic functions. Characterization of a panel of PTEN phosphorylation site mutants revealed that mutating Ser-385 to alanine (S385A) promoted membrane localization in vivo and phosphatase activity in vitro. Furthermore, S385A mutation was associated with a substantial reduction in the phosphorylation of the Ser-380/Thr-382/Thr-383 cluster. Therefore, Ser-385 could prime additional dephosphorylation events to regulate PTEN catalytic activity. Moreover, substituting Ser-380/Thr-382/Thr-383 to phosphomimic residues reversed the phosphatase activity of the S385A mutation. Next, we further defined the underlying mechanisms responsible for the COOH-terminal tail region in modulating PTEN biological activity. We have identified an interaction between the 71-amino acid carboxyl-terminal tail region and the CBRIII motif of the C2 domain, which has been implicated in membrane binding. In addition, a synthetic phosphomimic peptide encompassing the phosphorylation site cluster between amino acids 368 and 390 within the tail region mediated the suppression of PTEN catalytic activity in vitro. This same peptide when expressed in cultured cells also impeded PTEN membrane localization and enhanced phospho-Akt levels. Thus, our data suggest that the COOH-terminal tail can act as an autoinhibitory domain to control both PTEN membrane recruitment and phosphatase activity. The regulation of PTEN intrinsic biochemical properties has not been fully elucidated. In this report, we investigated the role of the PTEN carboxyl-terminal tail domain in regulating its membrane targeting and catalytic functions. Characterization of a panel of PTEN phosphorylation site mutants revealed that mutating Ser-385 to alanine (S385A) promoted membrane localization in vivo and phosphatase activity in vitro. Furthermore, S385A mutation was associated with a substantial reduction in the phosphorylation of the Ser-380/Thr-382/Thr-383 cluster. Therefore, Ser-385 could prime additional dephosphorylation events to regulate PTEN catalytic activity. Moreover, substituting Ser-380/Thr-382/Thr-383 to phosphomimic residues reversed the phosphatase activity of the S385A mutation. Next, we further defined the underlying mechanisms responsible for the COOH-terminal tail region in modulating PTEN biological activity. We have identified an interaction between the 71-amino acid carboxyl-terminal tail region and the CBRIII motif of the C2 domain, which has been implicated in membrane binding. In addition, a synthetic phosphomimic peptide encompassing the phosphorylation site cluster between amino acids 368 and 390 within the tail region mediated the suppression of PTEN catalytic activity in vitro. This same peptide when expressed in cultured cells also impeded PTEN membrane localization and enhanced phospho-Akt levels. Thus, our data suggest that the COOH-terminal tail can act as an autoinhibitory domain to control both PTEN membrane recruitment and phosphatase activity. PTEN is a bona fide tumor suppressor gene frequently inactivated in multiple human tumors (1Stiles B. Groszer M. Wang S. Jiao J. Wu H. Dev. Biol. 2004; 273: 175-184Crossref PubMed Scopus (206) Google Scholar, 2Parsons R. Semin. Cell Dev. Biol. 2004; 15: 171-176Crossref PubMed Scopus (201) Google Scholar, 3Maehama T. Dixon J.E. Trends Cell Biol. 1999; 9: 125-128Abstract Full Text Full Text PDF PubMed Scopus (506) Google Scholar, 4Eng C. Hum. Mutat. 2003; 22: 183-198Crossref PubMed Scopus (666) Google Scholar, 5Cantley L.C. Neel B.G. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 4240-4245Crossref PubMed Scopus (1754) Google Scholar, 6Myers M.P. Tonks N.K. Am. J. Hum. Genet. 1997; 61: 1234-1238Abstract Full Text Full Text PDF PubMed Scopus (79) Google Scholar, 7Backman S. Stambolic V. Mak T. Curr. Opin. Neurobiol. 2002; 12: 516-522Crossref PubMed Scopus (77) Google Scholar, 8Leslie N.R. Downes C.P. Biochem. J. 2004; 382: 1-11Crossref PubMed Scopus (349) Google Scholar). PTEN encodes a phosphatidylinositol (3Maehama T. Dixon J.E. Trends Cell Biol. 1999; 9: 125-128Abstract Full Text Full Text PDF PubMed Scopus (506) Google Scholar, 4Eng C. Hum. Mutat. 2003; 22: 183-198Crossref PubMed Scopus (666) Google Scholar, 5Cantley L.C. Neel B.G. Proc. Natl. Acad. Sci. U. S. A. 1999; 96: 4240-4245Crossref PubMed Scopus (1754) Google Scholar) triphosphate (PIP3) 4The abbreviations used are: PIP3, phosphatidylinositol 3,4,5-bisphosphate; aa, amino acid; CTD, COOH-terminal domain; DAPI, 4′,6-diamidino-2-phenylindole; PTPase, phosphatase; PIP2, phosphatidylinositol 4,5-bisphosphate; PMSF, phenylmethylsulfonyl fluoride; MES, 4-morpholineethanesulfonic acid; GFP, green fluorescent protein. phosphatase (PTPase) that plays a critical role in regulating the intracellular levels of PIP3 (9Maehama T. Dixon J.E. J. Biol. Chem. 1998; 273: 13375-13378Abstract Full Text Full Text PDF PubMed Scopus (2614) Google Scholar, 10Stambolic V. Suzuki A. de la Pompa J.L. Brothers G.M. Mirtsos C. Sasaki T. Ruland J. Penninger J.M. Siderovski D.P. Mak T.W. Cell. 1998; 95: 29-39Abstract Full Text Full Text PDF PubMed Scopus (2120) Google Scholar, 11Myers M.P. Pass I. Batty I.H. Van der Kaay J. Stolarov J.P. Hemmings B.A. Wigler M.H. Downes C.P. Tonks N.K. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 13513-13518Crossref PubMed Scopus (1013) Google Scholar). The mechanism by which PTEN targets the plasma membrane is under intense investigation. In addition, how the intrinsic catalytic activity of PTEN is regulated has not been fully delineated. The resolution of the PTEN crystal structure has provided biophysical data in identifying functional motifs responsible for mediating PTEN membrane binding (12Lee J.O. Yang H. Georgescu M.M. Di Cristofano A. Maehama T. Shi Y. Dixon J.E. Pandolfi P. Pavletich N.P. Cell. 1999; 99: 323-334Abstract Full Text Full Text PDF PubMed Scopus (883) Google Scholar). PTEN possesses in its carboxyl terminus between amino acids (aa) 186 and 351 a C2 domain, which is similar to that found in phospholipase C81. In particular, the conserved CBRIII loop possesses five positively charged and two hydrophobic residues that are implicated in phospholipids binding (12Lee J.O. Yang H. Georgescu M.M. Di Cristofano A. Maehama T. Shi Y. Dixon J.E. Pandolfi P. Pavletich N.P. Cell. 1999; 99: 323-334Abstract Full Text Full Text PDF PubMed Scopus (883) Google Scholar, 13Georgescu M.M. Kirsch K.H. Kaloudis P. Yang H. Pavletich N.P. Hanafusa H. Cancer Res. 2000; 60: 7033-7038PubMed Google Scholar, 14Das S. Dixon J.E. Cho W. Proc. Natl. Acad. Sci. U. S. A. 2003; 100: 7491-7496Crossref PubMed Scopus (283) Google Scholar). Additional positively charged residues interfacing the lipid bilayer at Arg-161, Lys-163, and Lys-164 have been shown to contribute to membrane binding through electrostatic interactions (14Das S. Dixon J.E. Cho W. Proc. Natl. Acad. Sci. U. S. A. 2003; 100: 7491-7496Crossref PubMed Scopus (283) Google Scholar). Consequently, these interactions orient the catalytic pocket toward the lipid bilayer. Based on protease sensitivity assays, the 7-aa NH2-terminal and 49-aa COOH-terminal regions of PTEN are unstructured and therefore unable to be crystallized (12Lee J.O. Yang H. Georgescu M.M. Di Cristofano A. Maehama T. Shi Y. Dixon J.E. Pandolfi P. Pavletich N.P. Cell. 1999; 99: 323-334Abstract Full Text Full Text PDF PubMed Scopus (883) Google Scholar). Nevertheless, structure-functional analysis of these regions has implicated their involvement in membrane binding and PTEN biological activities. The NH2-terminal 16-aa polybasic region constitutes a PIP2-binding motif that is essential for PTEN tumor suppressor function. Deletion of this region or the acquisition of a tumor-associated Lys → Glu-13 mutation greatly reduces PTEN membrane binding and tumor suppressing activity (15Walker S.M. Leslie N.R. Perera N.M. Batty I.H. Downes C.P. Biochem. J. 2004; 379: 301-307Crossref PubMed Scopus (130) Google Scholar, 16Campbell R.B. Liu F. Ross A.H. J. Biol. Chem. 2003; 278: 33617-33620Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar, 17Vazquez F. Devreotes P. Cell Cycle. 2006; 5: 1523-1527Crossref PubMed Scopus (77) Google Scholar, 18Iijima M. Huang Y.E. Luo H.R. Vazquez F. Devreotes P.N. J. Biol. Chem. 2004; 279: 16606-16613Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). PIP2 binding to this motif greatly stimulates the intrinsic catalytic activity of PTEN (16Campbell R.B. Liu F. Ross A.H. J. Biol. Chem. 2003; 278: 33617-33620Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar, 18Iijima M. Huang Y.E. Luo H.R. Vazquez F. Devreotes P.N. J. Biol. Chem. 2004; 279: 16606-16613Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). The fact that PIP2 fails to stimulate PTEN when a soluble lipid substrate, inositol 1,3,4,5-trisphosphate, was used argues for a role of a PIP2-rich membrane in orientating the catalytic pocket of PTEN toward the lipid bilayer (18Iijima M. Huang Y.E. Luo H.R. Vazquez F. Devreotes P.N. J. Biol. Chem. 2004; 279: 16606-16613Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar). However, it has also been suggested that PIP2 may activate PTEN through an allosteric mechanism (16Campbell R.B. Liu F. Ross A.H. J. Biol. Chem. 2003; 278: 33617-33620Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar). All of these findings favor an interfacial activation mechanism of PTEN at the lipid bilayer involving interactions of multiple membrane binding moieties (19McConnachie G. Pass I. Walker S.M. Downes C.P. Biochem. J. 2003; 371: 947-955Crossref PubMed Scopus (98) Google Scholar). The COOH-terminal 63-aa region (aa 347-399) of PTEN was initially referred to as the PEST domain (20Vazquez F. Grossman S.R. Takahashi Y. Rokas M.V. Nakamura N. Sellers W.R. J. Biol. Chem. 2001; 276: 48627-48630Abstract Full Text Full Text PDF PubMed Scopus (361) Google Scholar, 21Vazquez F. Ramaswamy S. Nakamura N. Sellers W.R. Mol. Cell. Biol. 2000; 20: 5010-5018Crossref PubMed Scopus (656) Google Scholar, T. 2000; PubMed Scopus Google Scholar). are phosphorylation at and Ser-385 that are implicated in modulating PTEN tumor suppressor and In PTEN mutants with these with amino acids have tumor suppressor enhanced membrane and (14Das S. Dixon J.E. Cho W. Proc. Natl. Acad. Sci. U. S. A. 2003; 100: 7491-7496Crossref PubMed Scopus (283) Google Scholar, F. Grossman S.R. Takahashi Y. Rokas M.V. Nakamura N. Sellers W.R. J. Biol. Chem. 2001; 276: 48627-48630Abstract Full Text Full Text PDF PubMed Scopus (361) Google Scholar, 21Vazquez F. Ramaswamy S. Nakamura N. Sellers W.R. Mol. Cell. Biol. 2000; 20: 5010-5018Crossref PubMed Scopus (656) Google Scholar, T. M. A. Cancer Res. 2001; 61: Google Scholar, J. R. J. Biol. Chem. 2001; 276: Full Text Full Text PDF PubMed Scopus Google Scholar, F. A. I. B. M. PubMed Scopus Google Scholar, F. H. Y. Maehama T. J. Biol. Chem. 2004; 279: Full Text Full Text PDF PubMed Scopus Google Scholar, J. J. M.P. M. Tonks N.K. R. J. Biol. Chem. 2003; 278: Full Text Full Text PDF PubMed Scopus Google Scholar, Y. Liu J. Wang H. J. Biol. Chem. 2003; 278: Full Text Full Text PDF PubMed Scopus Google Scholar, Y. S. T. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus (206) Google Scholar). The biochemical for these is to be the of a by these mutants F. Devreotes P. Cell Cycle. 2006; 5: 1523-1527Crossref PubMed Scopus (77) Google Scholar, F. Grossman S.R. Takahashi Y. Rokas M.V. Nakamura N. Sellers W.R. J. Biol. Chem. 2001; 276: 48627-48630Abstract Full Text Full Text PDF PubMed Scopus (361) Google Scholar). However, these phosphorylation contribute to the intrinsic catalytic activity of PTEN to be two at and Ser-385 have been shown to be in vivo Neel B.G. Biochem. 2002; PubMed Scopus Google Scholar). The biological of phosphorylation at and Ser-385 is not a of has been shown to have the J. R. J. Biol. Chem. 2001; 276: Full Text Full Text PDF PubMed Scopus Google Scholar). Additional phosphorylation at and have been to be the targets of is that phosphorylation at these constitutes a mechanism in events by Y. S. T. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus (206) Google Scholar). Furthermore, has been shown to and within the C2 domain of PTEN in cells to Wang Liu W. N. Y. T. R. Wu Cell. Biol. PubMed Scopus Google Scholar). The cluster of and residues in the tail region are phosphorylation Y. S. T. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus (206) Google Scholar, Neel B.G. Biochem. 2002; PubMed Scopus Google Scholar). However, has been to stimulate their in the of PTEN catalytic activity L.C. Perera N.M. Downes C.P. Leslie N.R. J. 2006; PubMed Scopus Google Scholar). Furthermore, has been identified as a site for its dephosphorylation greatly the of PTEN to in human M. S. A. S. A. 2004; PubMed Scopus Google Scholar). is in how the COOH-terminal domain of PTEN its biochemical function. In this report, we that this tail region interactions with the C2 In addition, the PEST domain in residues can as an autoinhibitory motif in suppressing PTEN catalytic activity. Cell human and human in with of cells in with of of in of and for of gene in cells on a with of of in of and for of of the has been T. 2000; PubMed Scopus Google Scholar, T. M. A. Cancer Res. 2001; 61: Google Scholar). the of PTEN and was All PTEN with and and the and of the The was by an the peptide in the and of the The was by a two to the NH2-terminal of and The was the and of and by encompassing of PTEN the of the and the the the the the the the and the The was a of and the COOH-terminal of The was the as the in phenylmethylsulfonyl and of was with of or for at of for at The with of in of and to in a of PMSF, and Cell with in a at for at The was at for at The was the The was in a PMSF, and and at for at The was the membrane in an MES, PMSF, and for on The by in a and was to The on the of an and and in MES, was on The for at at was with MES, and at for The for in and by in PMSF, and for on The for at The was as the The was in PMSF, and for at The was as the membrane and the to a on with cells with in and in at with was with an with and by on a with a of PTEN and or to and with at and in with PMSF, and by and and to and by at and was with for at PTEN was on a a The was through on a of PTEN cells with PTEN and for in and PTEN was as PTEN by this has an PIP3 phosphatase activity of PTEN was with synthetic with or synthetic both in soluble for at in a of The was in and The was with of green The of was by the at The of used was and within the of the The of was to the of used in the PTEN activity in cells with of of cells in of a PMSF, and of with of an for and of PTEN phosphatase activity was as PTEN was with synthetic in soluble in the of of the and and and and for at in a of The phosphatase was as The peptide as In in with of and of The was for at The was expressed in on a to a of of of The binding was of the in and of the in a of of binding of and The binding was at and the with the binding with of and by The was with and on a of PTEN in the of PTEN in the of PTEN was investigated in and cells with a by in the of PTEN found in the The levels of PTEN in the membrane under these has been the of a the of PTEN in the membrane to a in cells Y. K.H. M. P. Cancer Cell. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). The of was by and as the and membrane and In addition, the levels of PTEN in the of these in the Furthermore, by PTEN was not in the lipid All of these data with the localization of PTEN in cells Y. K.H. M. P. Cancer Cell. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar). of and Ser-385 in PTEN events in the region have been implicated in PTEN membrane binding (14Das S. Dixon J.E. Cho W. Proc. Natl. Acad. Sci. U. S. A. 2003; 100: 7491-7496Crossref PubMed Scopus (283) Google Scholar, 17Vazquez F. Devreotes P. Cell Cycle. 2006; 5: 1523-1527Crossref PubMed Scopus (77) Google Scholar). However, the of phosphorylation to membrane targeting in cells has not been a panel of PTEN phosphorylation site mutants was of site mutants and site and site a PTEN PTEN mutants and to the as in the to the site both and S385A and in the membrane when with The site has the membrane targeting which was that of the protein. the site mutants and not the protein. the and the a the role of phosphorylation at and Ser-385 in membrane we two phosphomimic and the the similar membrane when with the the the has a membrane binding the S385A further these we a PTEN by an to its a PTEN the NH2-terminal 16-aa PIP2-binding was The localization of these PTEN was by Next, the phosphorylation of these PTEN by the and revealed that PTEN has a reduction in phosphorylation of in phosphorylation at Ser-385 was this was not and Furthermore, phosphorylation levels at these two not in the of PTEN have the of phosphorylation site mutants F. Ramaswamy S. Nakamura N. Sellers W.R. Mol. Cell. Biol. 2000; 20: 5010-5018Crossref PubMed Scopus (656) Google Scholar, M. S. A. S. A. 2004; PubMed Scopus Google Scholar). However, how phosphorylation contribute to the catalytic of PTEN has not been PTEN mutants with a at the terminus and expressed in through a and PTEN was further by This was in in our PTEN by this PTEN a intrinsic phosphatase between PTEN mutants G. T. and A. M. PIP2 has been shown to PTEN lipid phosphatase activity (16Campbell R.B. Liu F. Ross A.H. J. Biol. Chem. 2003; 278: 33617-33620Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar, 18Iijima M. Huang Y.E. Luo H.R. Vazquez F. Devreotes P.N. J. Biol. Chem. 2004; 279: 16606-16613Abstract Full Text Full Text PDF PubMed Scopus (170) Google Scholar, G. Pass I. Walker S.M. Downes C.P. Biochem. J. 2003; 371: 947-955Crossref PubMed Scopus (98) Google PIP3 or PIP2 and PIP3 in used as in our shown in the site mutants and a in their catalytic activity when with the protein. However, these mutants to the of the the S385A and the and site mutants a in phosphatase activity. However, PIP2 to further stimulate their catalytic activity. mutants with enhanced catalytic their phosphorylation levels at and analysis revealed a reduction in phosphorylation at the and the Ser-380/Thr-382/Thr-383 cluster in the S385A and for the and a a activity when to the S385A Thus, phosphorylation at the Ser-380/Thr-382/Thr-383 cluster may be positively regulated by phosphorylation events at and PTEN with the C2 the of PTEN in membrane binding and we the two of we investigated could interactions with PTEN implicated in membrane binding. Next, the of the in PTEN activity was The of the region could favor interactions to regulate PTEN biochemical this functional of PTEN for their to with a COOH-terminal tail region encompassing in cells PTEN The the PTEN and an NH2-terminal with the COOH-terminal of similar was not when was an the was not in the when the was not This interaction was also by an CTD, Furthermore, the interaction was to be to the of the with a to We have further the binding between and in M. S. A. S. A. 2004; PubMed Scopus Google Scholar) have the interaction between the domain and the and that this interaction the of the We have this interaction similar PTEN and However, we to between the domain and the these we that the region of PTEN with the C2 and the that the PTEN may with the catalytic domain through with the C2 The with the CBRIII of the C2 the residues in the C2 domain in the interaction with the a panel of mutants was The of these mutants to the was We that the interaction was when residues this region to the CBRIII loop of the C2 domain implicated in membrane (12Lee J.O. Yang H. Georgescu M.M. Di Cristofano A. Maehama T. Shi Y. Dixon J.E. Pandolfi P. Pavletich N.P. Cell. 1999; 99: 323-334Abstract Full Text Full Text PDF PubMed Scopus (883) Google Scholar, 13Georgescu M.M. Kirsch K.H. Kaloudis P. Yang H. Pavletich N.P. Hanafusa H. Cancer Res. 2000; 60: 7033-7038PubMed Google Scholar). However, of of the residues at and to not binding to the Furthermore, substituting additional positively residues at the and also not the interaction between and Thus, these that the interaction between the and the C2 domain on multiple the interactions are in The the of PTEN in a on our the interaction between and the C2 domain could be the In addition, mutating phosphorylation within the PTEN to a intrinsic phosphatase activity. in autoinhibitory that could regulate intrinsic activities. Furthermore, PTEN a for and may the of in the tail region M. S. A. S. A. 2004; PubMed Scopus Google Scholar). the could act as an autoinhibitory domain, two The peptide the phosphorylation cluster between residues 368 and 390 of the phosphomimic was used with the at and to and the at and to The of these to the phosphatase activity of PTEN was PIP3 as a shown in the peptide PTEN activity with an of the peptide a with an of In addition, a peptide was to the peptide an similar to that of the the peptide could PTEN catalytic activity in cultured of and a phosphomimic in to the membrane localization of PTEN when with the control This was with a in in cells with the similar of was also in cells The fact that on PTEN could be by the fact that both and Ser-385 Thus, these that the phosphorylation cluster within the region plays an role in PTEN membrane targeting and catalytic activities. two have identified and Ser-385 as the phosphorylation of PTEN when expressed in cells Y. S. T. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus (206) Google Scholar, Neel B.G. Biochem. 2002; PubMed Scopus Google Scholar). We have used to a peptide encompassing of We found the peptide to be at This the that additional could be in the phosphorylation of and The panel of PTEN mutants has provided the role of phosphorylation in the intrinsic properties of the mutants we have the not the protein. has been that the phosphorylation at can prime the phosphorylation of by Y. S. T. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus (206) Google Scholar). However, mutating not in in PTEN not Thus, the biological of phosphorylation by is to alanine or acid PTEN PTEN to the membrane its phosphorylation PTEN at constitutes a of PTEN in Neel B.G. Biochem. 2002; PubMed Scopus Google Scholar). these we the two plays a role in regulating PTEN mutating to alanine or acid a in the tail region to The is that PTEN with constitutes a of PTEN that membrane binding. our data not the that phosphorylation of could PTEN membrane could be as by the We are to a of PTEN in to the of the with the Ser-385 mutants the of phosphorylation and dephosphorylation events at this site in regulating PTEN membrane binding and catalytic activities. We have shown that the S385A PTEN has the Thus, it is that dephosphorylation at Ser-385 membrane binding. has a in have been that phosphorylation at Ser-385 may prime the phosphorylation of by J. R. J. Biol. Chem. 2001; 276: Full Text Full Text PDF PubMed Scopus Google Scholar, Y. S. T. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus (206) Google Scholar, T. F. Y. Biochem. 2004; PubMed Scopus Google Scholar). by a we have a reduction in the of phosphorylation at these in both the S385A and However, we are unable to the phosphatase activity and membrane localization with these two mutants is to in Ser-385 and or it is an of the of phosphorylation at The phosphatase activity of the when with S385A to for the of dephosphorylation at is to that the an phosphorylation of not which residues are Thus, it is to in the the residues that are in the S385A is to suggest that phosphorylation events at or Ser-385 are these are to be and may a role in additional phosphorylation the the levels of phosphorylation at and have been shown to be in cells with L.C. Perera N.M. Downes C.P. Leslie N.R. J. 2006; PubMed Scopus Google N. G. F. W.R. Wang Y. I. Y. M. Res. 2002; PubMed Scopus Google J. 2003; PubMed Scopus Google and human F. J.L. B. I. M. J. Biochem. Mol. Biol. PubMed Scopus Google Scholar). In these phosphorylation PTEN lipid phosphatase activity. data that PTEN terminus possesses autoinhibitory functions. is mediated by the of both the C2 and phosphatase The that the can membrane binding through on positively charged residues has been (14Das S. Dixon J.E. Cho W. Proc. Natl. Acad. Sci. U. S. A. 2003; 100: 7491-7496Crossref PubMed Scopus (283) Google Scholar). the is to electrostatic interaction with residues at Arg-161, Lys-163, and Lys-164 in the NH2-terminal phosphatase domain our the is the of the interaction of the tail region with the C2 domain of The C2 domain of PTEN of the residues for binding (12Lee J.O. Yang H. Georgescu M.M. Di Cristofano A. Maehama T. Shi Y. Dixon J.E. Pandolfi P. Pavletich N.P. Cell. 1999; 99: 323-334Abstract Full Text Full Text PDF PubMed Scopus (883) Google Scholar). However, it possesses the CBRIII which is of five residues at and implicated in electrostatic interactions with the plasma the of the to the C2 domain was when the CBRIII motif was of positively charged residues not the Therefore, it is that the phosphorylation cluster within the could interaction with the C2 binding motifs within the PTEN may with the CBRIII region through a phosphomimic peptide the we have shown that it can PTEN catalytic activity in a that the as an autoinhibitory similar domain with has been for the phosphatase S. Biochem. J. PubMed Scopus Google Scholar). data to the that the phosphorylation between and Ser-385 could act as a with PIP3 for the catalytic are for the may as an by a with the catalytic is that the phosphorylation cluster can PTEN catalytic the fails to with the domain We that in for the phosphorylation cluster to with the catalytic the to by with the C2 The these interactions additional data biophysical Based on our data and it is to a in which the PTEN membrane targeting and catalytic activity. We favor a in which the PTEN its through a the an interaction with the CBRIII region of the C2 domain through This in the phosphorylation cluster between and to interaction with the catalytic pocket and PTEN activity. a PTEN a and in the the dephosphorylation of Ser-385 a of events that the catalytic pocket and the C2 PTEN this activation has a for plasma membrane and can PIP3 with We and for with