AKAP (A-kinase anchoring protein) domains: beads of structure–function on the necklace of G-protein signalling

2004 ◽  
Vol 32 (5) ◽  
pp. 861-864 ◽  
Author(s):  
C.C. Malbon ◽  
J. Tao ◽  
E. Shumay ◽  
H.-Y. Wang
Keyword(s):  
Structure Function ◽  
G Protein ◽  
Cell Signalling ◽  
Spatial Dimension ◽  
Binding Domain ◽  
Regulatory Subunit ◽  
Anchoring Proteins ◽  
G Protein Signalling ◽  
Anchoring Protein ◽  
G Protein Coupled

AKAPs (A-kinase anchoring proteins) are members of a diverse family of scaffold proteins that minimally possess a characteristic binding domain for the RI/RII regulatory subunit of protein kinase A and play critical roles in establishing spatial constraints for multivalent signalling assemblies. Especially for G-protein-coupled receptors, the AKAPs provide an organizing centre about which various protein kinases and phosphatases can be assembled to create solid-state signalling devices that can signal, be modulated and trafficked within the cell. The structure of AKAP250 (also known as gravin or AKAP12), based on analyses of milligram quantities of recombinant protein expressed in Escherichia coli, suggests that the AKAP is probably an unordered scaffold, acting as a necklace on which ‘jewels’ of structure–function (e.g. the RII-binding domain) that provide docking sites on which signalling components can be assembled. Recent results suggest that AKAP250 provides not only a ‘tool box’ for assembling signalling elements, but may indeed provide a basis for spatial constraint observed for many signalling paradigms. The spatial dimension of the integration of cell signalling will probably reflect many functions performed by members of the AKAP family.

scholarly journals AKAPs (A-kinase anchoring proteins) and molecules that compose their G-protein-coupled receptor signalling complexes

2004 ◽  
Vol 379 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Craig C. MALBON ◽  
Jiangchuan TAO ◽  
Hsien-yu WANG
Keyword(s):  
G Protein ◽  
Tyrosine Kinases ◽  
Cell Signalling ◽  
G Protein Coupled Receptors ◽  
Dynamic Regulation ◽  
Receptor Signalling ◽  
Anchoring Proteins ◽  
Β2 Adrenergic Receptor ◽  
Cytoskeletal Elements ◽  
G Protein Coupled

Cell signalling mediated via GPCRs (G-protein-coupled receptors) is a major paradigm in biology, involving the assembly of receptors, G-proteins, effectors and downstream elements into complexes that approach in design ‘solid-state’ signalling devices. Scaffold molecules, such as the AKAPs (A-kinase anchoring proteins), were discovered more than a decade ago and represent dynamic platforms, enabling multivalent signalling. AKAP79 and AKAP250 were the first to be shown to bind to membrane-embedded GPCRs, orchestrating the interactions of various protein kinases (including tyrosine kinases), protein phosphatases (e.g. calcineurin) and cytoskeletal elements with at least one member of the superfamily of GPCRs, the prototypical β2-adrenergic receptor. In this review, the multivalent interactions of AKAP250 with the cell membrane, receptor, cytoskeleton and constituent components are detailed, providing a working model for AKAP-based GPCR signalling complexes. Dynamic regulation of the AKAP–receptor complex is mediated by ordered protein phosphorylation.

scholarly journals The apelin receptor: physiology, pathology, cell signalling, and ligand modulation of a peptide-activated class A GPCR

2014 ◽  
Vol 92 (6) ◽  
pp. 431-440 ◽  
Author(s):  
Nigel A. Chapman ◽  
Denis J. Dupré ◽  
Jan K. Rainey
Keyword(s):  
G Protein ◽  
Cell Signalling ◽  
Wide Distribution ◽  
Peptide Ligand ◽  
Cellular Effects ◽  
Class A ◽  
Promising Therapeutic Target ◽  
Apelin Receptor ◽  
Obesity And Cancer ◽  
G Protein Coupled

The apelin receptor (AR or APJ) is a class A (rhodopsin-like) G-protein-coupled receptor with wide distribution throughout the human body. Activation of the AR by its cognate peptide ligand, apelin, induces diverse physiological effects including vasoconstriction and dilation, strengthening of heart muscle contractility, angiogenesis, and regulation of energy metabolism and fluid homeostasis. Recently, another endogenous peptidic activator of the AR, Toddler/ELABELA, was identified as having a crucial role in zebrafish (Danio rerio) embryonic development. The AR is also implicated in pathologies including cardiovascular disease, diabetes, obesity, and cancer, making it a promising therapeutic target. Despite its established importance, the precise roles of AR signalling remain poorly understood. Moreover, little is known about the mechanisms of peptide–AR activation. Additional complexity arises from modulation of the AR by 2 endogenous peptide ligands, both with multiple bioactive isoforms of variable length and distribution. The various apelin and Toddler/ELABELA isoforms may also produce distinct cellular effects. Further complexity arises through formation of functionally distinct heterodimers between the AR and other G-protein-coupled receptors. This minireview outlines key (patho)physiological actions of the AR, addresses what is known about signal transduction downstream of AR activation, and concludes by discussing unique properties of the endogenous peptidic ligands of the AR.

scholarly journals The Downstream Regulation of Chemokine Receptor Signalling: Implications for Atherosclerosis

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Jyoti Patel ◽  
Keith M. Channon ◽  
Eileen McNeill
Keyword(s):  
G Protein ◽  
Chemokine Receptors ◽  
Vascular Inflammation ◽  
Vascular Wall ◽  
Rgs Proteins ◽  
Cell Recruitment ◽  
Physiological Processes ◽  
G Protein Signalling ◽  
Atherosclerotic Plaque Formation ◽  
G Protein Coupled

Heterotrimeric G-protein-coupled receptors (GPCRs) are key mediators of intracellular signalling, control numerous physiological processes, and are one of the largest class of proteins to be pharmacologically targeted. Chemokine-induced macrophage recruitment into the vascular wall is an early pathological event in the progression of atherosclerosis. Leukocyte activation and chemotaxis during cell recruitment are mediated by chemokine ligation of multiple GPCRs. Regulation of GPCR signalling is critical in limiting vascular inflammation and involves interaction with downstream proteins such as GPCR kinases (GRKs), arrestin proteins and regulator of G-protein signalling (RGS) proteins. These have emerged as new mediators of atherogenesis by functioning in internalisation, desensitisation, and signal termination of chemokine receptors. Targeting chemokine signalling through these proteins may provide new strategies to alter atherosclerotic plaque formation and plaque biology.

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