Human 5-HT3A -- Tyr 217

Species Original Mutated to Mutation
Human Tyr 217 Gln, Lys


Rat Equivalent Lys 216    
Mouse Equivalent Gln 222 Tyr Q222Y



When the triplet mutation of hM223I, hE224D and hS225I was also combined with hY217Q and hR219K, there was a 26-fold increase in the IC50 of (+)-Tubocurarine relative to the human wild type. When this quintuple mutation was combined with hY228S and hV237I, there was a further decrement of 2-fold of the IC50 value of (+)-Tubocurarine relative to the quintuple mutant.

Hope AG, Belelli D, Mair ID, Lambert JJ, Peters JA (1999) Molecular Determinants of (+)- Tubocurarine Binding at Recombinant 5-Hydroxytryptamine3A Receptor Subunits. Molecular Pharmacology 55:1037-1043

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The mutation was made in the human 5-HT3A subunit at Tyr217. This residue was numbered Tyr194 in the paper in which numbering began at the end of the signal sequence.

In order to identify the potency of meta-chlorophenylbiguanide (mCPBG) in human 5-HT3A receptors, the recombinant human and rat 5-HT3A receptors were expressed in Xenopus Oocytes by cRNA injection and 5-HT-evoked currents were recorded using two-electorde voltage-clamp. The effect of replacing human Leu215, Pro216, Tyr217, Arg219, Met223, Ser225 and Tyr228 (numbering from the beginning of the signal sequence) by the equivalent residues (Phe, Thr, Lys,Gln, Ile, Thr and Ser) in the rat was to increase the potency of mCPBG as an agonist at the mutant human 5-HT3A receptor by 13-fold.

Mochizuki S.,Miyake A.,Furuichi K. (1999) Identification of a domain affecting agonist potency of meta-chlorophenylbiguanide in 5-HT3 receptors. European Journal of Pharmacology 369:125-132

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