Some proteins relocate from one plasma membrane compartment to another by means of trans-cytosis. However, not all proteins proceed directly to their eventual destination. The main family of adaptor proteins, which ensures the cellular targeting and correct signaling function for the metabotropic glutamate receptors, appear. įor family C receptors, the importance of and structural basis for interaction with intracellular adaptor or scaffolding proteins have been characterized in great detail, just as the issue of dimer formation is rather clear for these receptors. Also, interaction with other types of scaffolding proteins such as PSD-95- like proteins, is influenced by the phosphorylation state of the receptor. This post-translational modification alters the affinity of the receptor for various intracellular proteins, including arrestin, which sterically prevents further G- protein binding and functions as an adaptor protein. Īs described in more detail below, agonist binding will lead to signaling as well as phosphorylation of Ser and Thr residues, especially, but also, in selected cases, Tyr residues located in intracellular loop-3 and in the C-terminal extension. Soluble mimics of a chemokine receptor chemokine binding by receptor elements juxtaposed on a soluble scaffold. J Neuro592 Santello M, Volterra A (2008) Synaptic modulation by astrocytes via Ca(2-l-)-dependent glutamate release.
J Neurosci Res 84 1098-1106 Sala C, Roussignol G, Meldolesi J, Fagni L (2005) Key role of the postsynaptic density scaffold proteins Shank and Homer in the functional architecture of Ca homeostasis at dendritic spines in hippocampal neurons. Saez ET, Pehar M, Vargas MR, Barbeito L, Maccioni RB (2006) Production of nerve growth factor by beta-amyloid-stimulated astrocytes induces p75NTR-dependent tau hyperphosphorylation in cultured hippocampal neurons. It also binds 4A and 4B, the ATPase-hehcase complex that helps unwind the RNA (Figure 38-7). In addition to binding 4E, 4G binds to elF-3, which hnlcs the complex to the 40S ribosomal subunit. As described above, 4F is a complex consisting of 4E, which binds to the m G cap strucmre at the 5 end of the mRNA, and 4G, which serves as a scaffolding protein. The 4F complex is particularly important in controUing the rate of protein translation. Filamins are a family of actin polymerization proteins that also form scaffolds for a range of signaling proteins including SAP kinases such as MKK-4, small GTPases Rho and Ras, as well as Smad 2 and Smad 5. SARA is a scaffolding protein that regulates the subcellular localization of inactivated R-Smads, potentially scaffolding the TGF-P receptor kinase to the Smad 2 substrate. This applies to ser/thr protein phosphatases as well as to tyrosine phosphatases. Some of these anchoring proteins bind both, kinases and phosphatases. Numerous protein phosphatases are targeted to their substrates and regulators through the interaction with specific scaffolding proteins. AChE-R can intra-cellularly interact through its C- terminal tail with the Protein Kinase C Receptor RACK1, a scaffold protein which modifies multiple cellular processes. Therefore, it remains soluble, and its secreted form shows greater mobility than AChE-S. ĪChE-R (in purple) Naturally rare, stress-induced variant, which lacks a hydrophobic domain and is incapable of binding to ColQ or PRiMA. a particular hormone or neurotransmitter).
This compartmentalization of signalling by AKAPs contributes to the specificity of a cellular response to a given external stimulus (e.g. AKAPs tether PKA and other signalling proteins to cellular compartments and thereby limit and integrate cellular signalling processes at specific sites. They are defined by the presence of a structurally conserved protein kinase A (PKA)- binding domain. AKAPs are a diverse family of about 75 scaffolding proteins.