Classification, Nomenclature, and Structural Aspects of Adhesion GPCRs

Area of Science:

• Cellular Biology
• Molecular Biology
• Genetics

Background:

• Adhesion G protein-coupled receptors (aGPCRs) are characterized by long N-termini and multiple domains involved in cell-cell and cell-matrix interactions.
• Phylogenetic classification initially grouped human aGPCRs into nine subfamilies based on 7TM sequence similarity, a grouping conserved across vertebrates.
• Diverse nomenclature historically hindered clear communication, necessitating a standardized system.

Purpose of the Study:

• To review the classification and propose a unified nomenclature for adhesion G protein-coupled receptors (aGPCRs).
• To discuss the structural topology of the extracellular domain (ECD)/N-terminal fragment (NTF) in relation to the 7TM subfamily classification.
• To systematically describe ECD structural domains and their functions in aGPCR-protein interactions.

Main Methods:

• Phylogenetic analysis of aGPCRs based on 7TM sequence similarity.
• Review of existing literature and expert consensus for nomenclature harmonization.
• Systematic description of structural domains within the extracellular domain (ECD) of aGPCR subfamilies.

Main Results:

• Established a unified nomenclature for aGPCRs, facilitating consistent naming across species.
• Demonstrated congruence between phylogenetic subfamily classification and extracellular domain (ECD) structural topology.
• Detailed the structural domains within the ECD of aGPCR subfamilies and their roles in protein interactions.

Conclusions:

• The proposed unified nomenclature and classification system for aGPCRs enhance clarity and consistency in research.
• Understanding the structural diversity of aGPCR ECDs is crucial for elucidating their functions in cell adhesion and signaling.
• This framework supports future exploration of aGPCRs in pharmacology and disease.