A role of Histidine151 in the lamprey gonadotropin-releasing hormone receptor-1 (lGnRHR-1): Functional insight of diverse amino acid residues in the position of Tyr of the DRY motif in GnRHR from an ancestral type II receptor

Abstract

The highly conserved DRY motif located at the end of the third transmembrane of G proteincoupled receptors has been described as a key motif for several aspects of GPCR functions. However, in the case of the vertebrate gonadotropin-releasing hormone receptor (GnRHR), the amino acid in the third position in the DRY motif is variable. In the lamprey, a most basal vertebrate, the third amino acid of the "DRY" in GnRHR is His, while it is most often His/Gln in the type II GnRHR. To investigate the functional significance of the substitution of DRY to DRH in the lamprey(l)GnRHR, second messenger signaling, ligand binding and internalization of the wild-type and mutant lGnRH receptors were characterized with site-directed mutagenesis. Treatment of the DRE 151 and DRS 151 mutant receptors with lamprey GnRH-I significantly reduced inositol phosphate compared to wild-type (DRH 151 ) and DRY 151 receptors. The logIC 50 of wild-type receptor (−9.554±0.049) was similar to the logIC 50 of DRE 151 , DRS 151 and DRX 151 mutants, yet these same mutants were shown to significantly reduce cell surface expression. However, the DRY 151 mutant compared to the wild-type receptor increased cell surface expression, suggesting that the reduction of IP production was due to the level of the cell surface expression of the mutant receptors. The rate of internalization of DRX 151 (35.60%) was reduced compared to wild-type and other mutant receptors. These results suggest that His 151 of the lamprey GnRH receptor may play a critical role in the retention of a certain level of cell-surface expression for subsequent cellular second messenger events.

‘Crystal’ Clear? Lysophospholipid Receptor Structure Insights and Controversies

“…MD indicated the ERH maintains LPA 1 in a locked conformation by forming an intrahelical lock with L256 6.33 [29, 50, 54]. There is little information about the role of H 3.51 , but mutational analyses of the lamprey gonadotropinreleasing hormone receptor (GnRH) wild-type H 3.51 indicated involvement in maintaining the receptor at the cell surface [57]. LPA 6 has a more conventional DRF motif.…”

Lampreys: Biology, Conservation and Control

“…However, in the case of the vertebrate gonadotropin-releasing hormone receptor (GnRHR), the amino acid in the third position in the DRY motif is variable. To investigate the functional significance of the substitution of DRY to DRH in the GnRHR-1, second messenger signaling, ligand binding, and internalization of the wild-type and mutant lGnRH receptors were characterized with site-directed mutagenesis (Kosugi and Sower 2010). There are variable substitutions of the third amino acid in the DRY motif of GnRHRs from different classes of vertebrates.…”