PDBsum entry 3qc9

Transferase

PDB id: 3qc9

Contents

Protein chains

486 a.a.

Ligands

ADP ×4

GOL ×2

Metals

_MG ×8

Waters ×113

References listed in PDB file

Key reference

• Title: Activation of g protein-Coupled receptor kinase 1 involves interactions between its n-Terminal region and its kinase domain.
• Authors: C.C.Huang, T.Orban, B.Jastrzebska, K.Palczewski, J.J.Tesmer.
• Ref.: Biochemistry, 2011, 50, 1940-1949.
• PubMed id: 21265573

Abstract

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 in which 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 does not dictate the affinity of GRKs for activated receptors.