title: Lectin-induced enhancement of voltage-dependent calcium flux and calcium channel antagonist binding.
abstract: Concanavalin A (Con A), a tetravalent lectin with preferential affinity for mannosyl and glucosyl residues of membrane glycoconjugates, increased K+ depolarization-evoked uptake of 45Ca2+ in the PC12 neural cell line. Enhancement of uptake by Con A was concentration dependent, with maximal (24%) stimulation at 100 micrograms/ml of Con A, and was preferentially inhibited by mannoside and glucoside. Succinyl-Con A, a divalent analog with reduced biological potency, increased uptake by only 7%. The effect of Con A on 45Ca2+ uptake was dependent on membrane depolarization, was abolished by ionic Ca2+ channel blockers and organic Ca2+ channel antagonists, and was accompanied by an equivalent increase in Ca2+ channel 3H-labeled antagonist binding, observations suggesting that the voltage-dependent Ca2+ channel was the site of Ca2+ entry. The mechanism for enhancement of 45Ca2+ uptake by Con A appeared to be separate from that used by the Ca2+ channel agonist BAY K 8644 and independent of that involved in Ca2+ channel regulation by phorbol esters. These findings suggest that voltage-dependent Ca2+ channels may link cell surface carbohydrate interactions with intracellular effector processes.
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology*; D003208:Concanavalin A / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism*; D008358:Mannose / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D009432:Neural Crest / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D002132:Calcium Radioisotopes; D007473:Ion Channels; D003208:Concanavalin A; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D005947:Glucose; D013755:Tetradecanoylphorbol Acetate; D008358:Mannose; D011188:Potassium; D002118:Calcium