Jv. Cook et al., EFFECTS OF ASN(87) AND ASP(318) MUTATIONS ON LIGAND-BINDING AND SIGNAL-TRANSDUCTION IN THE RAT GNRH RECEPTOR, Journal of Endocrinology, 139(3), 1993, pp. 180000001-180000004
The gonadotrophin-releasing hormone (GnRH) receptor is unlike other G-
protein coupled receptors in that the highly conserved amino acids, As
p in the second transmembrane region and Asn in the seventh, are inter
changed. Site-directed mutagenesis studies mutated these residues back
to their normally conserved positions. Two single mutants Asn(87)Asp
& Asp(318)Asn and one double mutant Asn(87)Asp Asp(318)Asn were transi
ently expressed in COS-I cells and their effect on binding to GnRH and
inositol phosphate production measured. The single mutant Asp(318)Asn
had no effect on ligand binding but abolished GnRH-dependent inositol
phosphate production, whereas mutations Asn(87)Asp and Asn(87)Asp Asp
(318)Asn show a complete loss of GnRH binding and subsequent inactivat
ion of its second messenger system.