Pharmacological study on recombinant human GABA-A receptor complex containing alpha5 (leucine155 to valine) combined with beta3gamma2s subunits.
OBJECTIVE
To investigate the characterization of the pharmacology of recombinant human GABA-A receptor complex containing alpha5beta3gamma2s subunits, and clarify which amino acids are essential for binding affinity.


METHODS
We constructed chimeric subunit of alpha5 (leucine mutated to valine in 155) by site-directed mutation, combined alpha5 or alpha5 (valine 155) with beta3gamma2s subunits by using the baculovirus-transfected Sf-9 insect cell expressing system. Fifteen commercially available effective compounds for the GABA binding recognition site were determined.


RESULTS
We found that competitive antagonist SR95531 and inhibitor Thio-4-piol increased IC50 values about 3 folds in alpha5 (valine155) beta3gamma2s compare to alpha5 (leucine155) beta3gamma2s receptor subunit combinations; Other GABA-A receptor ligands have little difference.


CONCLUSIONS
The amino acid residues in 155 is important for the binding affinity and efficacy of SR95531 and Thio-4-piol to GABA-A receptor combinations containing an alpha5 subunit.
Wang
X K
XK
Department of Pharmacognosy, Beijing University of Traditional Chinese Medicine, Beijing 100029, China. Wangxiukun@263.net
D000818:Animals; D018756:GABA Antagonists / Q000737:chemistry / Q000494:pharmacology; D007930:Leucine; D016297:Mutagenesis, Site-Directed; D011724:Pyridazines / Q000737:chemistry / Q000494:pharmacology; D011963:Receptors, GABA-A / Q000096:biosynthesis / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D018411:Spodoptera / Q000166:cytology / Q000378:metabolism; D014633:Valine
D018756:GABA Antagonists; D011724:Pyridazines; D011963:Receptors, GABA-A; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; C049853:gabazine; D007930:Leucine; D014633:Valine