Critical implication of transmembrane Phe310, possibly in conjunction withTrp279, in the rat gonadotropin-releasing hormone receptor activation

Citation
S. Chauvin et al., Critical implication of transmembrane Phe310, possibly in conjunction withTrp279, in the rat gonadotropin-releasing hormone receptor activation, BIOCH PHARM, 62(3), 2001, pp. 329-334
Citations number
37
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Pharmacology & Toxicology
Journal title
BIOCHEMICAL PHARMACOLOGY
ISSN journal
0006-2952 → ACNP
Volume
62
Issue
3
Year of publication
2001
Pages
329 - 334
Database
ISI
SICI code
0006-2952(20010801)62:3<329:CIOTPP>2.0.ZU;2-Z
Abstract
The GnRH-R belongs to the superfamily of heptahelical GPCRs. A three-dimens ional model of GnRH binding to its receptor predicted that Trp3 was the mos t deeply buried residue, potentially allowing it to interact with both Trp2 79, a highly conserved residue in the TMH 6 of GPCRs, and Phe310, present e ssentially in TMH 7 of GnRH-Rs. Replacement of Phe310 with Leu, the most co mmon positional residue in GPCRs, induced a slightly decreased B-max (1.6-f old) and affinity (3.8-fold); in addition, IP production was completely abo lished. Similarly, replacement of Trp279 with Ser depressed the B-max by 5. 2-fold, the affinity by 2.3-fold, and totally abrogated IP production. The effect of the double mutation was not additive on binding, since the B-max was reduced to the level of the Phe310Leu mutant, although the K-d was rest ored to a value not significantly different from that of the wild-type. The double mutant was also unable to induce TP production. Unexpectedly, no in fluence of any single or double substitution was noted on receptor internal ization. These data provide evidence for the crucial role of Phe310, possib ly in conjunction with Trp279, on GnRH transduction and suggest that the co nformation for phospholipase C activation may not be required fur GnRH-R in ternalization. (C) 2001 Elsevier Science Inc. All rights reserved.