Molecular scaffold protein and cellular responses

Mitogen-activated kinases (MAPK) regulate many diverse cellular processes, including growth, differentiation and responses to stress. The organization of MAPKs through the use of scaffolding proteins is crucial for the select ive activation of these kinases by different stimuli. Recent studies identi fy beta -arrestins as members of the family of MAPK scaffold proteins. beta -Arrestins not only shut off signaling by uncoupling G-protein-coupled rec eptors (GPCRs) from their heterotrimeric G proteins, but also contribute to the specificity of GPCRs signaling by recruiting and activating selective MAPKs.