A role of Histidine(151) 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

作者：Kosugi Takayoshi; Sower Stacia A^*

来源：General and Comparative Endocrinology, 2010, 166(3): 498-503.

DOI：10.1016/j.ygcen.2009.12.001

• GnRH receptor
• DRY motif
• Receptor expression
• Signaling
• Site-directed mutagenesis
• Lamprey

The highly conserved DRY motif located at the end of the third transmembrane of G-protein-coupled 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 lamprey (lGnRHR-1) 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 GnRHR-1, second messenger signaling, ligand binding and internalization of the wild-type and mutant lGnRH receptors were characterized with site-directed mutagenesis. Treatment of the DRE151 and DRS151 mutant receptors with lamprey GnRH-I significantly reduced inositol phosphate compared to wild-type (DRH151) and DRY151 receptors. The Log IC50 of wild-type receptor (-9.554 +/- 0.049) was similar to the Log IC50 of DRE151, DRS151 and DRX151 mutants, yet these same mutants were shown to significantly reduce cell-surface expression. However, the DRY151 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 DRX151 (35.60%) was reduced compared to wild-type and other mutant receptors. These results suggest that His(151) of the lamprey GnRH receptor-1 may play a critical role in the retention of a certain level of cell-surface expression for subsequent cellular second messenger events.

• 出版日期2010-5-1