7TM Domain Structure of Adhesion GPCRs

Area of Science:

• Structural biology
• Biochemistry
• Pharmacology

Background:

• Recent advances in G protein-coupled receptor (GPCR) structural biology have not yet yielded a structure for the adhesion GPCR (aGPCR) family.
• The seven-transmembrane (7TM) domain is crucial for GPCR function, but its structure in aGPCRs remains largely unknown.

Purpose of the Study:

• To provide an overview of the current knowledge regarding the 7TM domain of aGPCRs.
• To compare aGPCRs with GPCRs of known crystal structure, focusing on sequence similarity and potential structural homology.
• To elucidate conserved sequence motifs and their potential roles in aGPCR ligand interactions and activation mechanisms.

Main Methods:

• Comparative structure-based sequence similarity analyses between aGPCRs and GPCRs with known crystal structures.
• Emphasis on comparison with the secretin family of GPCRs, which exhibits sequence similarity to aGPCRs.
• Analysis of known 7TM domain structures of secretin family GPCRs (e.g., GCGR) and integration of experimental data (mutagenesis, EM, HDX).

Main Results:

• The secretin family of GPCRs shares sequence similarity with aGPCRs, suggesting a potential shared structural fold for their 7TM domains.
• Conserved sequence motifs present in both aGPCRs and secretin family GPCRs likely play important roles in intermolecular interactions and conformational changes.
• The ligand-binding pocket in the aGPCR 7TM domain appears to be relatively hydrophobic and potentially larger than that of secretin family GPCRs.

Conclusions:

• The 7TM domains of aGPCRs and secretin family GPCRs likely share a similar structural fold.
• Conserved residues may mediate similar interaction networks and conformational dynamics across these GPCR families.
• Further understanding of conserved motifs is essential for deciphering aGPCR ligand interactions and activation mechanisms.