凝集素诱导的电压依赖性钙通量增强及钙通道拮抗剂结合

Lectin-induced enhancement of voltage-dependent calcium flux and calcium channel antagonist binding.

作者信息

Greenberg D A, Carpenter C L, Messing R O

出版信息

J Neurochem. 1987 Mar;48(3):888-94. doi: 10.1111/j.1471-4159.1987.tb05600.x.

DOI:10.1111/j.1471-4159.1987.tb05600.x

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.

摘要

伴刀豆球蛋白A（Con A）是一种对膜糖缀合物的甘露糖基和葡萄糖基残基具有优先亲和力的四价凝集素，它能增加PC12神经细胞系中K⁺去极化诱发的⁴⁵Ca²⁺摄取。Con A对摄取的增强作用呈浓度依赖性，在100微克/毫升Con A时刺激作用最大（24%），且优先被甘露糖苷和葡萄糖苷抑制。琥珀酰-Con A是一种生物活性降低的二价类似物，其摄取增加仅7%。Con A对⁴⁵Ca²⁺摄取的影响取决于膜去极化，被离子型Ca²⁺通道阻滞剂和有机Ca²⁺通道拮抗剂消除，并伴有Ca²⁺通道³H标记拮抗剂结合的等效增加，这些观察结果表明电压依赖性Ca²⁺通道是Ca²⁺进入的位点。Con A增强⁴⁵Ca²⁺摄取的机制似乎与Ca²⁺通道激动剂BAY K 8644所使用的机制不同，且独立于佛波酯对Ca²⁺通道的调节机制。这些发现表明电压依赖性Ca²⁺通道可能将细胞表面碳水化合物相互作用与细胞内效应过程联系起来。