AGONIST PHARMACOLOGY OF NEONATAL AND ADULT GLYCINE RECEPTOR ALPHA-SUBUNITS - IDENTIFICATION OF AMINO-ACID-RESIDUES INVOLVED IN TAURINE ACTIVATION

作者：SCHMIEDEN V^*; KUHSE J; BETZ H

来源：The EMBO Journal, 1992, 11(6): 2025-2032.

DOI：10.1002/j.1460-2075.1992.tb05259.x

• GLYCINE RECEPTOR
• AGONIST RESPONSE
• HETEROLOGOUS EXPRESSION LIGAND BINDING
• SITE-DIRECTED MUTAGENESIS

The inhibitory glycine receptor (GlyR) is a pentameric chloride channel protein which mediates postsynaptic inhibition in the mammalian central nervous system. In spinal cord, different GlyR isoforms originate from the sequential expression of developmentally regulated variants of the ligand binding alpha-subunit. Here, neonatal-alpha-2 and adult-alpha-1 subunits are shown to generate GlyRs with distinct agonist activation profiles upon heterologous expression in Xenopus oocytes. Whereas alpha-1 receptors are efficiently gated by beta-alanine and taurine, alpha-2 GlyRs show only a low relative response to these agonists, which also display a reduced sensitivity to inhibition by the glycinergic antagonist strychnine. Construction of an alpha-2/alpha-1 subunit chimera and site-directed mutagenesis of the extracellular region of the alpha-1 sequence identified amino acid positions 111 and 212 as important determinants of taurine activation. Our results indicate the existence of distinct subsites for agonists on alpha-1 and alpha-2 GlyRs and suggest that the ligand binding pocket of these receptor proteins is formed from discontinuous domains of their extracellular region.

• 出版日期1992-6