SEVENS: a database for comprehensive GPCR genes obtained from genomes: -Update to 68 eukaryotes

Empirical Potential Energy Function Toward ab Initio Folding G Protein-Coupled Receptors

Approximately 40-50 percent of all drugs targets are G protein-coupled receptors (GPCRs). Three-dimensional structure of GPCRs is important to probe their biophysical and biochemical functions and their pharmaceutical applications. Lacking reliable and high quality free function is one of the ugent problems of computational predicting the three-dimensional structure in this community. We proposed a GPCR-specified energy function composed of four novel empirical potential energy terms: a two-dimensional contact energy force field, knowledge-based helix pair connection distance energy term, knowledge-based helix pair angle restraint energy term and a disulfide bond energy term. To validate the energy function, we employed an ab initio GPCR three-dimensional structure predictor to test if the energy function improved the accuracy of prediction. We evaluated 28 solved GPCRs and found that 21(75 percent) targets were correctly folded (TM-score>0.5). Also, the average TM-score using the energy function was 0.54, which was improved 134 percent than the TM-score 0.23 for MODELLER energy function and 170 percent than the TM-score 0.20 for Rosetta membrane energy function. The results confirmed that our empirical potential energy function toward ab initio folding is competitive to state-of-the-art solutions for structural prediction of GPCRs.

G protein-coupled receptors in acquired epilepsy: Druggability and translatability

As the largest family of membrane proteins in the human genome, G protein-coupled receptors (GPCRs) constitute the targets of more than one-third of all modern medicinal drugs. In the central nervous system (CNS), widely distributed GPCRs in neuronal and nonneuronal cells mediate numerous essential physiological functions via regulating neurotransmission at the synapses. Whereas their abnormalities in expression and activity are involved in various neuropathological processes. CNS conditions thus remain highly represented among the indications of GPCR-targeted agents. Mounting evidence from a large number of animal studies suggests that GPCRs play important roles in the regulation of neuronal excitability associated with epilepsy, a common CNS disease afflicting approximately 1-2% of the population. Surprisingly, none of the US Food and Drug Administration (FDA)-approved (>30) antiepileptic drugs (AEDs) suppresses seizures through acting on GPCRs. This disparity raises concerns about the translatability of these preclinical findings and the druggability of GPCRs for seizure disorders. The currently available AEDs intervene seizures predominantly through targeting ion channels and have considerable limitations, as they often cause unbearable adverse effects, fail to control seizures in over 30% of patients, and merely provide symptomatic relief. Thus, identifying novel molecular targets for epilepsy is highly desired. Herein, we focus on recent progresses in understanding the comprehensive roles of several GPCR families in seizure generation and development of acquired epilepsy. We also dissect current hurdles hindering translational efforts in developing GPCRs as antiepileptic and/or antiepileptogenic targets and discuss the counteracting strategies that might lead to a potential cure for this debilitating CNS condition.

The role of β-arrestins in G protein-coupled receptor heterologous desensitization: A brief story

G protein-coupled receptors (GPCRs) are transmembrane proteins that have an important impact in a myriad of cellular functions. Posttranslational modifications on GPCRs are a key processes that allow these proteins to recruit other intracellular molecules. Among these modifications, phosphorylation is the most important way of desensitization of these receptors. Several research groups have described two different desensitization mechanisms: heterologous and homologous desensitization. The first one involves the phosphorylation of the receptors by protein kinases, such as PKC, following the desensitization and internalization of the receptor, while the second one involves the phosphorylation of the receptors by GRKs, allowing for the receptor to recruit β-arrestins to be desensitized and internalized. Interestingly, a few number of studies have described the participation of β-arrestins during the heterologous desensitization process. Hence, the aim of this review is to briefly explore the role that β-arrestins play during the heterologous desensitization of several GPCRs.