Dataset Information

The structure of p85ni in class IA phosphoinositide 3-kinase exhibits interdomain disorder.

ABSTRACT: Regulation of the class IA PI 3-kinase involves inhibition and stabilization of the catalytic subunit (p110) by the regulatory subunit (p85). Regulation is achieved by two major contacts: a stable interface involving the adapter-binding domain (ABD) of p110 and the inter-SH2 (iSH2) domain of p85 and a regulatory interaction between the N-terminal SH2 (nSH2) domain of p85 and the helical domain of p110. In the present study, we have examined the relative orientation of the nSH2 and iSH2 of p85alpha using site-directed spin labeling and pulsed EPR. Surprisingly, both distance measurements and distance distributions suggest that the nSH2 domain is highly disordered relative to the iSH2 domain. Molecular modeling based on EPR distance restraints suggests that the nSH2 domain moves in a hinge-like manner, sampling a torus space around the proximal end of the iSH2 domain. These data have important implications for the mechanism by which p85/p110 dimers are regulated by phosphopeptides.

SUBMITTER: Sen KI

PROVIDER: S-EPMC2849757 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The structure of p85ni in class IA phosphoinositide 3-kinase exhibits interdomain disorder.

Sen K Ilker KI Wu Haiyan H Backer Jonathan M JM Gerfen Gary J GJ

Biochemistry 20100301 10

Regulation of the class IA PI 3-kinase involves inhibition and stabilization of the catalytic subunit (p110) by the regulatory subunit (p85). Regulation is achieved by two major contacts: a stable interface involving the adapter-binding domain (ABD) of p110 and the inter-SH2 (iSH2) domain of p85 and a regulatory interaction between the N-terminal SH2 (nSH2) domain of p85 and the helical domain of p110. In the present study, we have examined the relative orientation of the nSH2 and iSH2 of p85alp ...[more]

PMID: 20131869

Similar Datasets

Project description:We have addressed the differential roles of class I Phosphoinositide 3-kinases (PI3K) in human breast-derived MCF10a (and iso-genetic derivatives) and MDA-MB 231 and 468 cells. Class I PI3Ks are heterodimers of p110 catalytic (?, ?, ? and ?) and p50-101 regulatory subunits and make the signaling lipid, phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3) that can activate effectors, eg protein kinase B (PKB), and responses, eg migration. The PtdIns(3,4,5)P3-3-phosphatase and tumour-suppressor, PTEN inhibits this pathway. p110?, but not other p110s, has a number of onco-mutant variants that are commonly found in cancers. mRNA-seq data shows that MCF10a cells express p110?>>?>? with undetectable p110?. Despite this, EGF-stimulated phosphorylation of PKB depended upon p110?-, but not ?- or ?- activity. EGF-stimulated chemokinesis, but not chemotaxis, was also dependent upon p110?, but not ?- or ?- activity. In the presence of single, endogenous alleles of onco-mutant p110? (H1047R or E545K), basal, but not EGF-stimulated, phosphorylation of PKB was increased and the effect of EGF was fully reversed by p110? inhibitors. Cells expressing either onco-mutant displayed higher basal motility and EGF-stimulated chemokinesis.This latter effect was, however, only partially-sensitive to PI3K inhibitors. In PTEN(-/-) cells, basal and EGF-stimulated phosphorylation of PKB was substantially increased, but the p110-dependency was variable between cell types. In MDA-MB 468s phosphorylation of PKB was significantly dependent on p110?, but not ?- or ?- activity; in PTEN(-/-) MCF10a it remained, like the parental cells, p110?-dependent. Surprisingly, loss of PTEN suppressed basal motility and EGF-stimulated chemokinesis. These results indicate that; p110? is required for EGF signaling to PKB and chemokinesis, but not chemotaxis; onco-mutant alleles of p110? augment signaling in the absence of EGF and may increase motility, in part, via acutely modulating PI3K-activity-independent mechanisms. Finally, we demonstrate that there is not a universal mechanism that up-regulates p110? function in the absence of PTEN.

Dataset Information

The structure of p85ni in class IA phosphoinositide 3-kinase exhibits interdomain disorder.

Publications

The structure of p85ni in class IA phosphoinositide 3-kinase exhibits interdomain disorder.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets