Regulation of AKAP-Membrane Interactions by Calcium

• Published in: The Journal of biological chemistry 2006-08, Vol.281 (33), p.23932-23944
• Main Authors: Tao, Jiangchuan, Shumay, Elena, McLaughlin, Stuart, Wang, Hsien-yu, Malbon, Craig C.
• Format: Article
• Language: English
• Subjects: A Kinase Anchor Proteins; Amino Acid Sequence; Biological Transport; Calcium - chemistry; Calcium - metabolism; Calmodulin - chemistry; Calmodulin - metabolism; Cell Cycle Proteins - chemistry; Cell Cycle Proteins - metabolism; Cell Cycle Proteins - physiology; Cell Line, Tumor; Cell Membrane - metabolism; Cyclic AMP-Dependent Protein Kinases - metabolism; Humans; Intracellular Fluid - chemistry; Intracellular Fluid - metabolism; Intracellular Signaling Peptides and Proteins - chemistry; Lipid Bilayers - metabolism; Membrane Proteins - chemistry; Membrane Proteins - metabolism; Molecular Sequence Data; Myristic Acid - metabolism; Myristoylated Alanine-Rich C Kinase Substrate; Protein Binding; Protein Structure, Tertiary; Receptors, Adrenergic, beta-2 - metabolism; Static Electricity
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M601813200

The AKAP gravin is a scaffold for protein kinases, phosphatases, and adaptor molecules obligate for resensitization and recycling of β2-adrenergic receptors. Gravin binds to the receptor through well characterized protein-protein interactions. These interactions are facilitated ∼1000-fold when gravin is anchored to the cytoplasmic leaflet of the plasma membrane. Although the N-terminal region (∼550 residues) is highly negatively charged and probably natively unfolded, it could anchor gravin to the inner leaflet through hydrophobic insertion of its N-terminal myristate and electrostatic binding of three short positively charged domains (PCDs). Loss of the site of N-myristoylation was found to affect neither AKAP macro-scopic localization nor AKAP function. Synthetic peptides corresponding to PCD1-3 bound in vitro to unilamellar phospholipid vesicles with high affinity, a binding reversed by calmodulin in the presence of Ca2+. In vivo gravin localization is regulated by intracellular Ca2+, a function mapping to the N terminus of the protein harboring PCD1, PCD2, and PCD3. Mutation of any two PCDs eliminates membrane association of the non-myristoylated gravin, the sensitivity to Ca2+/calmodulin, and the ability of this scaffold to catalyze receptor resensitization and recycling.