Sequence-structure based phylogeny of GPCR Class A Rhodopsin receptors

Area of Science:

• Biochemistry
• Genomics
• Pharmacology

Background:

• Current G protein-coupled receptors (GPCRs) phylogenetic classification methods are sequence-dependent, limiting their effectiveness for highly divergent sequences with low sequence identity.
• Understanding GPCR Class A Rhodopsin superfamily evolution is crucial for functional annotation and drug development.

Purpose of the Study:

• To evolve a novel phylogenetic classification method for GPCR Class A Rhodopsin superfamily using sequence structure profiles.
• To identify potential ligand associations for orphan and unclassified Class A GPCRs.

Main Methods:

• Sequence structure profile-based alignment was generated using PROMALS3D.
• Phylogenetic analysis was performed using MEGA 5 software with Neighbor-Joining and Maximum Likelihood methods (1000 bootstrap replicates).

Main Results:

• Potential ligand associations were identified for numerous orphan and unclassified Class A GPCRs.
• Specific examples include GPR21/GPR52 with fatty acids, GPR75 with Neuropeptide Y, and GPR88/GPR135/GPR161/GPR101 with 11-cis-retinal.
• The study provides a refined understanding of GPCR Class A evolution and function.

Conclusions:

• The developed sequence structure profile-based method offers a robust approach for GPCR classification, overcoming limitations of sequence-only methods.
• Findings facilitate re-classification of GPCRs, selection of homology modeling templates, and identification of cross-reactive ligands.
• This research has significant implications for understanding GPCRs' role in disease modulation and guiding future therapeutic strategies.