Human 5-HT3A -- Ser 270

Species Original Mutated to Mutation
Human Ser 270  


Rat Equivalent Ser 275    
Mouse Equivalent Ser 275 Cys, Ala S275C, S275A


Simultaneous mutation of this residue and all other putative phosphorylation sites (replacement by alanine) in the mouse (cloned from NCB-20 cells) 5-HT3A receptor's intracellular loops (TM1-2 and TM3-4) failed to affect modulation by ethanol. Recombinant 5-HT3A receptors were expressed in Xenopus Oocytes (cRNA injection) and 5-HT-evoked currents were recorded using two-electrode voltage-clamp. The effect of replacing all intracellular Ser, Thr and Tyr (by Ala) was to shift the 5-HT concentration-response relationship slightly to the left (more potent).

Machu TK, Coultrap SJ, Waugh MD, Hamilton ME. (1999) Mutation of putative phosphorylation sites in the 5-hydroxytryptamine3 receptor does not eliminate its modulation by ethanol. Alcohol Clin Exp Res. 23(1):12-7


After the application of 1mM MTSET with 10uM 5-HT, there was no significant change. After the application of 1mM MTSES with 10uM 5-HT, there was no significant change.


Reeves DC, Goren EN, Akabas MH, Lummis SCR (2001) Structural and Electrostatic Properties of the 5-HT3 Receptor Pore Revealed by Substituted Cysteine Accessibility Mutagenesis. The Journal of Biological Chemistry 276(45):42035-42042


  Wild Type S275C
EC50 1.67 +/- 0.09 1.62 +/- 0.07
Hill Coefficient 2.0 +/- 0.1 3.2 +/- 0.2
Mg Inhibition (before MTSET) -41 +/- 3 -40 +/- 3
Mg Inhibition (after MTSET) -39 +/- 3 -15 +/- 2
Deactivation T50 ratio 0.95 +/- 0.03 3.77 +/- 0.79


Panicker S, Cruz H, Arrabit C, Slesinger PA (2002) Evidence for a Centrally Located Gate in the Pore of a Serotonin-Gated Ion Channel. The Journal of Neuroscience 22(5): 1629-1639


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