3qc9

Publication Abstract from PubMed

G protein-coupled receptor kinases (GRKs) phosphorylate activated G protein-coupled receptors (GPCRs) to initiate receptor desensitization. In addition to the canonical phosphoacceptor site of the kinase domain, activated receptors bind to a distinct docking site that confers higher affinity and activates GRKs allosterically. Recent mutagenesis and structural studies support a model wherein receptor docking activates a GRK by stabilizing the interaction of its ~20 amino acid N-terminal region with the kinase domain. This interaction in turn stabilizes a closed, more active conformation of the enzyme. To investigate the importance of this interaction for the process of GRK activation, we first validated the functionality of the N-terminal region in rhodopsin kinase (GRK1) by site-directed mutagenesis and then introduced a disulfide bond to cross-link the N-terminal region of GRK1 with its specific binding site on the kinase domain. Characterization of the kinetic and biophysical properties of the cross-linked protein showed that disulfide bond formation greatly enhances the catalytic efficiency of the peptide phosphorylation, but receptor-dependent phosphorylation, Meta II stabilization, and inhibition of transducin activation were unaffected. These data indicate that the interaction of the N-terminal region with the kinase domain is important for GRK activation, but that it does not dictate the affinity of GRKs for activated receptors.

Activation of G protein-coupled receptor kinase 1 involves interactions between its N-terminal region and its kinase domain.,Huang CC, Orban T, Jastrzebska B, Palczewski K, Tesmer JJ Biochemistry. 2011 Jan 25. PMID:21265573^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.