Revisiting the classification of adhesion GPCRs.

Area of Science:

• Molecular Biology
• Genomics
• Biochemistry

Background:

• G protein-coupled receptors (GPCRs) are a large family of cell surface receptors involved in diverse physiological processes.
• Current classification systems for GPCRs, including adhesion GPCRs (aGPCRs), have limitations and inconsistencies.
• Many aGPCRs remain orphan receptors with undefined functions and signaling pathways.

Purpose of the Study:

• To reassess the phylogenetic relationships of adhesion GPCRs (aGPCRs) across vertebrate and invertebrate species.
• To identify shortcomings in existing aGPCR subclassification schemes.
• To propose an updated classification system for aGPCRs.

Main Methods:

• Phylogenetic analysis of aGPCR sequences from various species.
• Comparison of existing classification systems (ABC and GRAFS) with new phylogenetic data.
• Evaluation of the need for functional data in GPCR classification.

Main Results:

• Secretin receptor-like GPCRs likely evolved from ancestral aGPCRs.
• Existing aGPCR subfamilies require revision, necessitating the inclusion of functional data.
• Novel aGPCR subfamilies are needed to classify invertebrate aGPCR sequences.
• Phylogenetic analysis revealed inconsistencies in current aGPCR classifications.

Conclusions:

• The current classification of adhesion GPCRs (aGPCRs) is inadequate and requires updating.
• A revised taxonomy integrating phylogenetic and functional data is essential for a clear understanding of aGPCRs.
• The proposed classification will improve the organization and study of aGPCRs across the animal kingdom.