Proper receptor signalling in a mutant catfish gonadotropin-releasing hormone receptor lacking the highly conserved Asp 90 residue

Abstract

The negatively charged side chain of an Asp residue in transmembrane domain 2 is likely to play an important role in receptor signalling since it is highly conserved in the whole family of G protein-coupled receptors, except in mammalian gonadotropin-releasing hormone (GnRH) receptors. In this paper we show that the conserved Asp 90 of the catfish GnRH receptor can be substituted by a neutral Asn 90 without abolishing receptor signalling if another negatively charged Glu 93 is introduced in a proximal region of the receptor interior, thereby mimicking the Glu 90–Lys 121 salt bridge of mammalian GnRH receptors.