Human 5-HT3A -- Glu 220

Species Original Mutated to Mutation
Human

Glu 220

Gln

Asp

E220Q

E220D

Rat Equivalent Glu 219    
Mouse Equivalent Glu 225 Ala

E225A

 

hGlu220Gln

EC50 (uM) Granisetron Inhibition (IC50) (nM) [3H]mCPBG (Kd) [3H]MCPBG (Granisetron Inhibition Ki) (nM) [3H] GR65630 (Kd) [3H]GR65630 (Granisetron Inhibition Ki) (nM) [3H]GR65630 (mCPBG Inhibition Ki)
Wild Type 2.1 +/- 0.6 0.14 +/- 0.1 12.7 +/- 1.9 2.0 +/- 0.6 1.4 +/- 0.3 1.4 +/- 0.4 11 +/- 4
E220Q 7.5 +/- 3.3 0.47 +/- 0.3 13.0 +/- 4.5 2.4 +/- 0.4 4.5 +/- 0.7 6 +/- 2 9 +/- 4

 

Schreiter C, Hovius R, Costioli M, Pick H, Kellenberger S, Schild L, Vogel H (2003) Characterization of the Ligand-Binding Site of the Serotonin 5-HT3 Receptor. The Journal of Biological Chemistry 278(25):22709-22716


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hGlu220Asp

EC50 (uM) Granisetron Inhibition (IC50) (nM) [3H]mCPBG (Kd) [3H]MCPBG (Granisetron Inhibition Ki) (nM) [3H] GR65630 (Kd) [3H]GR65630 (Granisetron Inhibition Ki) (nM) [3H]GR65630 (mCPBG Inhibition Ki)
Wild Type 2.1 +/- 0.6 0.14 +/- 0.1 12.7 +/- 1.9 2.0 +/- 0.6 1.4 +/- 0.3 1.4 +/- 0.4 11 +/- 4
E220D 21 +/- 5 1.2 +/- 0.4 37 +/- 5 7.0 +/- 1.5 12 +/- 3 11 +/- 4 41 +/- 11


Schreiter C, Hovius R, Costioli M, Pick H, Kellenberger S, Schild L, Vogel H (2003) Characterization of the Ligand-Binding Site of the Serotonin 5-HT3 Receptor. The Journal of Biological Chemistry 278(25):22709-22716


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mGlu225Ala

In this study amino acids from E225 to Y234 of a murine 5-HT3ASR were individually mutated to alanine. Conservative mutations were made if the initial alanine mutation showed no binding and/or function. The mutated receptors were evaluated using radioligand binding, two-electrode voltage clamp, and immunofluorescence studies.

The E225A mutation caused a 4-fold reduction in the Kd value for [3H]granisetron, with no significant changes to Bmax. There was a 10-fold reduction in the Ki value for 5-HT, with a 3.2-fold reduction in the EC50 value, and a significant decrease to Imax. No significant changes were seen in the Ki value for mCPBG. However, there was a 3-fold reduction in the EC50 value and a significant decrease in Imax for mCPBG.

Suryanarayanan A, Joshi PR, Bikádi Z, Mani M, Kulkarni TR, Gaines C, Schulte MK. (2005) The loop C region of the murine 5-HT3A receptor contributes to the differential actions of 5-hydroxytryptamine and m-chlorophenylbiguanide. Biochemistry 44(25):9140-9.

 

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