title: Specific binding of the calcium antagonist [3H]verapamil to membrane fractions from plants.
abstract: Specific binding of the Ca2+ channel blocker [3H] verapamil to a membrane fraction from plants has been characterized. Binding to zucchini membranes was saturable and reversible. The apparent equilibrium dissociation constant is KD = 102 nM and the maximum number of binding sites is Bmax = 60 pmol/mg of protein. The KD determined from the association and dissociation rate constants is 130 nM. [3H]Verapamil binding to zucchini membranes could not be inhibited by the Ca2+ antagonists nifedipine and diltiazem. However, [3H]verapamil could be displaced by diltiazem but not by nifedipine from corn membranes. Sucrose density fractionation of zucchini membrane preparations revealed that [3H]verapamil binding sites are located primarily at the plasma membrane.
authors.forename: E
authors.initials: E
authors.lastname: Andrejauskas
authors.forename: R
authors.initials: R
authors.lastname: Hertel
authors.forename: D
authors.initials: D
authors.lastname: Marmé
mesh_terms: D001665:Binding Sites; D004110:Diltiazem / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008566:Membranes / Q000378:metabolism; D009543:Nifedipine / Q000031:analogs & derivatives / Q000378:metabolism; D009568:Nitrendipine; D010944:Plants / Q000378:metabolism*; D014700:Verapamil / Q000378:metabolism*
chemical_list: D009568:Nitrendipine; D014700:Verapamil; D004110:Diltiazem; D009543:Nifedipine