Characterization of determinants of ligand binding to the nicotinic acid receptor GPR109A (HM74A/PUMA-G).

Article Details

Citation

Tunaru S, Lattig J, Kero J, Krause G, Offermanns S

Characterization of determinants of ligand binding to the nicotinic acid receptor GPR109A (HM74A/PUMA-G).

Mol Pharmacol. 2005 Nov;68(5):1271-80. Epub 2005 Aug 11.

PubMed ID
16099840 [ View in PubMed
]
Abstract

The G-protein-coupled receptor GPR109A (HM74A/PUMA-G) has recently been shown to function as a receptor for nicotinic acid (niacin) and to mediate its antilipolytic effects. Nicotinic acid is able to strongly raise plasma levels of high-density lipoprotein cholesterol, a property that distinguishes nicotinic acid from other lipid-lowering drugs. To investigate the structural determinants of GPR109A ligand binding, we performed site-directed mutagenesis of putative ligand binding residues combined with generation of chimeric receptors consisting of GPR109A and its close relative GPR109B, which does not bind nicotinic acid. We could identify Asn86/Trp91 [transmembrane helix (TMH) 2/extracellular loop (ECL) 1], Arg111 (TMH3), Ser178 (ECL2), Phe276 (TMH7), and Tyr284 (TMH7) as amino acid residues critical for binding of nicotinic acid. Together with data from molecular modeling studies, our data suggest that the ligand binding pocket for nicotinic acid of GPR109A is distinct from that of most other group A receptors. Although Arg111 at TMH3 serves as the basic anchor point for the carboxylate ligands, the ring system of nicotinic acid is embedded between Trp91 at the junction TMH2/ECL1 and Phe276/Tyr284 at TMH7. The heterocyclic ring is also bound to Ser178 at ECL2 via an H-bond. These data will facilitate the design of new antidyslipidemic drugs acting via GPR109A.

DrugBank Data that Cites this Article

Drug Targets
DrugTargetKindOrganismPharmacological ActionActions
NiacinHydroxycarboxylic acid receptor 2ProteinHumans
Yes
Agonist
Details
NiacinHydroxycarboxylic acid receptor 3ProteinHumans
Yes
Agonist
Details