Phosphorylation of the PTEN tail acts as an inhibitory switch by preventing its recruitment into a protein complex.
PTEN is a tumor suppressor protein that functions, in large part, by dephosphorylating the lipid second messenger phosphatidylinositol 3,4,5-trisphosphate and by doing so antagonizing the action of phosphoinositide 3-kinase. PTEN structural domains include an N-terminal phosphatase domain, a lipid-binding C2 domain, and a 50-amino acid C-terminal tail that contains a PDZ binding sequence. We showed previously that phosphorylation of the PTEN tail negatively regulates PTEN activity. We now show that phosphorylated PTEN exists in a monomeric "closed" conformation and has low affinity for PDZ domain-containing proteins. Conversely, when unphosphorylated, PTEN is in an "open" conformation, is recruited into a high molecular weight complex (PTEN-associated complex), and strongly interacts with PDZ-containing proteins such as MAGI-2. As a consequence, when compared with wild-type PTEN, the phosphorylation-deficient mutant form of PTEN strongly cooperates with MAGI-2 to block Akt activation. These results indicate that phosphorylation of the PTEN tail causes a conformational change that results in the masking of the PDZ binding domain. Consequently, the ability of PTEN to bind to PDZ domain-containing proteins is reduced dramatically. These data suggest that phosphorylation of the PTEN tail suppresses the activity of PTEN by controlling the recruitment of PTEN into the PTEN-associated complex.
Vazquez
F
F
Department of Adult Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.
Grossman
S R
SR
Takahashi
Y
Y
Rokas
M V
MV
Nakamura
N
N
Sellers
W R
WR
D030301:Activin Receptors, Type II; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D051528:Guanylate Kinases; D006801:Humans; D007527:Isoenzymes; D008954:Models, Biological; D009097:Multienzyme Complexes / Q000378:metabolism; D009703:Nucleoside-Phosphate Kinase / Q000378:metabolism; D051059:PTEN Phosphohydrolase; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011506:Proteins; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D007527:Isoenzymes; D009097:Multienzyme Complexes; D011506:Proteins; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; C494918:AKT1 protein, human; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D030301:Activin Receptors, Type II; D009703:Nucleoside-Phosphate Kinase; D051528:Guanylate Kinases; C485777:MAGI2 protein, human; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human