3 D modeling of the activated states of constitutively active mutants of rhodopsin q
نویسندگان
چکیده
The activated (R*) states in constitutively active mutants (CAMs) of G-protein-coupled receptors (GPCRs) are presumably characterized by lower energies than the resting (R) states. If specific configurations of TM helices differing by rotations along the long transmembrane axes possess energies lower than that in the R state for pronounced CAMs, but not for non-CAMs, these particular configurations of TM helices are candidate 3D models for the R* state. The hypothesis was studied in the case of rhodopsin, the only GPCR for which experimentally determined 3D models of the R and R* states are currently available. Indeed, relative energies of the R* state were significantly lower than that of the R state for the rhodopsin mutants G90D/M257Y and E113Q/M257Y (strong CAMs), but not for G90D, E113Q, and M257Y (not CAMs). Next, the developed build-up procedure successfully identified few similar configurations of the TM helical bundle of G90D/M257Y and E113Q/M257Y as possible candidates for the 3D model of the R* state of rhodopsin, all of them being in good agreement with the model suggested by experiment. Since constitutively active mutants are known for many of GPCRs belonging to the large rhodopsin-like family, this approach provides a way for predicting possible 3D structures corresponding to the activated states of the TM regions of many GPCRs for which CAMs have been identified. ! 2006 Elsevier Inc. All rights reserved.
منابع مشابه
Constitutive activation of G protein-coupled receptors and diseases: insights into mechanisms of activation and therapeutics.
The existence of constitutive activity for G protein-coupled receptors (GPCRs) was first described in 1980s. In 1991, the first naturally occurring constitutively active mutations in GPCRs that cause diseases were reported in rhodopsin. Since then, numerous constitutively active mutations that cause human diseases were reported in several additional receptors. More recently, loss of constitutiv...
متن کاملActive site-directed inactivation of constitutively active mutants of rhodopsin.
Recently, mutations of the active site Lys296 residue in rhodopsin (Lys296-->Glu and Lys296-->Met) have been found as the cause of disease in some patients with autosomal dominant retinitis pigmentosa. In vitro, these mutations result in constitutive activation of the protein. In an effort to develop a potential therapeutic agent for treatment of the disease, we have examined various amine deri...
متن کاملStabilized G protein binding site in the structure of constitutively active metarhodopsin-II.
G protein-coupled receptors (GPCR) are seven transmembrane helix proteins that couple binding of extracellular ligands to conformational changes and activation of intracellular G proteins, GPCR kinases, and arrestins. Constitutively active mutants are ubiquitously found among GPCRs and increase the inherent basal activity of the receptor, which often correlates with a pathological outcome. Here...
متن کاملA constitutively active somatic mutation of the human lutropin receptor found in Leydig cell tumors activates the same families of G proteins as germ line mutations associated with Leydig cell hyperplasia.
Using a Leydig tumor cell line (MA-10) transiently transfected with the human lutropin receptor (hLHR) and mutants thereof, we examined the identity of the G proteins activated by the agonist-engaged hLHR-wild type (wt) and by three of its naturally occurring constitutively active mutants. Two of the mutants examined, L457R in transmembrane helix 3 and D578Y in transmembrane helix 6, are germ-l...
متن کاملStructure and function in rhodopsin: covalent crosslinking of the rhodopsin (metarhodopsin II)-transducin complex--the rhodopsin cytoplasmic face links to the transducin alpha subunit.
We prepared rhodopsin mutants that contained a single reactive cysteine residue per rhodopsin molecule at position 65, 140, 240, or 316 on the cytoplasmic face. A carbene-generating photoactivatable group was linked by a disulfide bond to the cysteine sulfhydryl group of each of the rhodopsin mutants. The resulting derivative was then light-activated at lambda > 495 nm to form the metarhodopsin...
متن کامل