2,3-butanedione inactivates the [H-3]nitrendipine binding sites, whereas diethylpyrocarbonate does not

The modification of [H-3]nitrendipine binding sites in rabbit brain membranes with 2,3-butanedione and diethylpyrocarbonate was investigated. 2,3-Butanedione, an arginine-specific reagent, causes a dose- and time-dependent decrease in the number of [H-3]nitrendipine binding sites without altering its dissociation constant. Scatchard analysis of the binding data shows that 50 mM 2,3-butanedione decreases the binding capacity of [H-3]nitrendipine from a control value of 71 +/- 6 fmol/mg of protein to 40 +/- 3 fmol/mg of protein. Complete and selective protection against inactivation is provided by nifedipine. No decrease of [H-3]nitrendipine binding occurs when membranes are pretreated with selective histidine reagent diethylpyrocarbonate. The results indicate that arginine but not histidine residue in L-type calcium channel domain is critical for [H-3]nitrendipine binding. Copyright (C) 1996 Elsevier Science Ltd