Order and disorder in large multi-site docking proteins of the Gab family—implications for signalling complex formation and inhibitor design strategies

Abstract

Large multi-site docking (LMD) proteins of the Gab, IRS, FRS, DOK and Cas families consist of one or two folded N-terminal domains, followed by a predominantly disordered C-terminal extension. Their primary function is to provide a docking platform for signalling molecules (including PI3K, PLC, Grb2, Crk, RasGAP, SHP2) in intracellular signal transmission from activated cell-surface receptors, to which they become coupled. A detailed analysis of the structural nature and intrinsic disorder propensity of LMD proteins, with Gab proteins as specific examples, is presented. By primary sequence analysis and literature review the varying levels of disorder and hidden order are predicted, revealing properties and a physical architecture that help to explain their biological function and characteristics, common for network hub proteins. The virulence factor, CagA, from Helicobacter pylori is able to mimic Gab function once injected by this human pathogen into stomach epithelial cells. Its predicted differential structure is compared to Gab1 with respect to its functional mimicry. Lastly, we discuss how LMD proteins, in particular Gab1 and Gab2, and their protein partners, such as SH2 and SH3 domain-containing adaptors like Grb2, might qualify for future anti-cancer strategies in developing protein-protein interaction (PPI) inhibitors towards binary interactors consisting of an intrinsically disordered epitope and a structured domain surface.

The Signaling Adapter, FRS2, Facilitates Neuronal Branching in Primary Cortical Neurons via Both Grb2- and Shp2-Dependent Mechanisms

“…Herein, we demonstrate that FRS2 recruits both Grb2 and Shp2 at predicted pTyr binding sites in response to tyrosine phosphorylation by both NGFactivated TrkA in non-neuronal cells as well as in response to BDNF/NT-3 stimulation in primary mouse cortical neurons. Moreover, we demonstrate that Grb2 binding to FRS2 mediates the recruitment of both Gab1 and Gab2 adapters, that BDNF/NT3 stimulate the transient tyrosine phosphorylation of FRS2, Shp2, and Gab1/2 (maximal phosphorylation at 2-5 min with a gradual decline over the following 30 min), and that the Gab adapters show basal interactions with Grb2 in cortical neuron cultures but demonstrate an increase in their interaction with Shp2 following neurotrophin stimulation presumably via SH2 domain-mediated binding of Shp2 to the phosphorylated binding sites (V/LXpYXXV/L) on Gab1/2 (Simister and Feller 2012). With the use of recombinant adenoviruses, we overexpressed WT-FRS2, WT-FRS3, as Cortical neurons were infected with recombinant adenoviruses expressing FRS2 and its mutants FRS2 2A and FRS2 4A, in the absence of additional growth factors.…”

MAPK-induced Gab1 translocation to the plasma membrane depends on a regulated intramolecular switch

“…Previously, we could demonstrate that the presence of PIP3 in the PM, which 31 is increased in many cancer cells, is not sufficient for constitutive Gab1 membrane recruitment. In addition, 32 MAPK-dependent phosphorylation of Gab1 at serine 552 (Ser552) is vital for Gab1 membrane binding. Here, 33 we confirm our hypothesis that in the absence of MAPK activity an intrinsic part of Gab1 prevents binding to 34 PIP3 at the PM.…”

“…[32] for an alignment of the human Gab proteins bound to PIP3 protect the lipid from dephosphorylation by PTEN [31].…”

Study on the Anti-hypertension mechanism of Prunella Vulgaris based on entity grammar systems

“…It mediates the interaction between receptor tyrosine kinases (RTKs) and non-RTK receptors serving as the gateway into the cell for activation of SHP2, Phosphatidylinositol 3-kinase (PI3K), Grb2, ERK, AKT and acting as one of the first steps in these signaling pathways. The C-terminal tail of GAB2 acts as a site for multiplephosphorylation of tyrosine kinases (Simister et al, 2012).…”