Src docks to AKAP Gravin, regulating Beta-adrenergic receptor resensitization and recycling

Gravin (AKAP12) is a membrane-associated scaffold that provides docking for protein kinases, phosphatases, and adaptor molecules obligate for resensitization and recycling of beta(2)-adrenergic receptors. Gravin binds to the cell membrane in a Ca(2+)-sensitive manner and to receptors through well-characterized protein-protein interactions. Although the interaction of serine/threonine, cyclic AMP-dependent protein kinase with A-kinase-anchoring proteins is well-described and involves a kinase regulatory subunit binding domain in the C-terminus of these proteins, far less is known about tyrosine kinase docking to the members of this family of scaffolds. The non-receptor tyrosine kinase Src regulates resensitization of beta(2)-adrenergic receptors and docks to gravin. Gravin displays nine proline-rich domains distributed throughout the molecule. One class I ligand for Src homology domain 3 docking, found in the N-terminus ((10)RXPXXP(15)) of gravin, is shown to bind Src. Binding of Src to gravin activates the intrinsic tyrosine kinase of Src. Mutagenesis/deletion of the class I ligand (Pro15,16Ala) on the N-terminus of gravin abolishes both the docking of Src to gravin as well as the receptor resensitization and recycling catalyzed by gravin. The Src-binding peptide (1-51) of gravin behaves as a dominant-negative for AKAP gravin regulation of receptor resensitization/recycling. The tyrosine kinase Src plays an essential role in the AKAP gravin-mediated receptor resensitization and recycling, an essential aspect of receptor biology.