SOLUBILIZATION, CHARACTERIZATION AND PHOTOAFFINITY-LABELING OF THE MITOCHONDRIAL DIHYDROPYRIDINE RECEPTOR FROM BOVINE ADRENAL-MEDULLA

1. The mitochondrial dihydropyridine receptor was solubilized with Cha ps at a detergent/ protein ratio of 2.5, during 45 min at 4 degrees C. 2. From the rate constants of association (8.10+/-0.25 x 10(4) M(-1) min(-1)) and dissociation (0.022+/-0.001 min(-1)) a K-d of 275 nM was calculated while from saturation experiments a K-d of 270+/-30 nM and a density of receptors of 106+/-9 pmol/mg protein was obtained. 4. The solubilized receptors are heat-resistant, sensitive to the trypsin an d to the reduction of disulfide bonds. 5. In native membranes. a polyp eptide of 50 kDa was specifically photolabelled with [H-3]Azidopine.