OR1B1 and other olfactory receptor proteins are members of a large family of G-protein-coupled receptors (GPCR) arising from single coding-exon genes. Olfactory receptors share a 7-transmembrane domain structure with many neurotransmitter and hormone receptors and are responsible for the recognition and G protein-mediated transduction of odorant signals. The olfactory receptor gene family is the largest in the genome. A stop codon in the gene coding for this protein is responsible for functional diversity. The stop codon is more frequent in non-Africans than in African-Americans.