Hyperekplexia mutation R271L of alpha sub(1) glycine receptors potentiates allosteric interactions of nortropeines, propofol and glycine with [ super(3)H]strychnine binding

Human alpha sub(1) and hyperekplexia mutant alpha sub(1)(R271L) glycine receptors (GlyRs) were transiently expressed in human embryonic kidney 293 cells for [ super(3)H]strychnine binding. Binding parameters were determined using a ternary allosteric model. The hyperekplexia mutation increased the positive cooperativity of 0.3 mM propofol and glycine binding by about six times: the cooperativity factor beta was 0.26 for alpha sub(1) GlyRs and 0.04 for alpha sub(1)(R271L) GlyRs. Thus, propofol restored the potency of glycine impaired by the mutation. Five nortropeines, i.e. substituted benzoates of nortropine and a new compound, nortropisetron were prepared and also examined on [ super(3)H]strychnine binding. They showed nanomolar displacing potencies amplified by the hyperekplexia mutation. The affinity of nor-O-zatosetron (2.6 nM) is one of the highest reported for GlyRs. This binding test offers an in vitro method to evaluate agents against neurological disorders associated with inherited mutations of GlyRs.