Effects of canatoxin on the Ca(2+)-ATPase of sarcoplasmic reticulum membranes.
Canatoxin, a toxic protein isolated from the seeds of Canavalia ensiformis, was studied for its effects on the sarcoplasmic reticulum vesicles obtained from rabbit skeletal muscle. Canatoxin inhibited Ca2+ accumulation catalysed by the Ca(2+)-ATPase, without affecting the hydrolytic activity of this enzyme or membrane permeability to Ca2+. The effects of canatoxin were dose dependent, but not time dependent. It is concluded that canatoxin interacts with the Ca2+ pump and uncouples Ca2+ uptake from Ca(2+)-dependent ATP hydrolysis.
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Departamento de Bioquimica Medica, Instituto de Ciencias Biomedicas, Universidade Federal do Rio de Janeiro, Brazil.
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Carlini
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D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D066298:In Vitro Techniques; D037102:Lectins / Q000494:pharmacology*; D008566:Membranes / Q000187:drug effects / Q000201:enzymology; D009132:Muscles / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000201:enzymology*; D014118:Toxins, Biological
D037102:Lectins; D010940:Plant Proteins; D014118:Toxins, Biological; C032815:canatoxin; D000255:Adenosine Triphosphate; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D002118:Calcium