TABLE 1.

Pharmacological specificity of R-[³H]mTFD-MPAB photoincorporation into residues in the α1β3 GABA_AR (cpm/pmol PTH-derivative)

Photolabeled amino acids were identified in α1β3 GABA_AR purified in 0.2 mm asolectin, 5 mm CHAPS after photolabeling with 1.6 μm R-[³H]mTFD-MPAB. The efficiency of photolabeling of a residue (in cpm/pmol) was calculated using Equation 3 (see “Experimental Procedures”). ND means not determined.

Amino acid	Control	+R-mTFD-MPAB (60 μm)	+Etomidate (200 μm)
βM1 β3Met-227	7,100	140	5,200
βM3 β3Met-286	170	14	8
βM3 β3Phe-289	220	10	8
αM3 α1Tyr-294	150	ND	ND