Himehabu Lectin, a Novel Inducer of Ca2+-release from the Venom of the Snake Trimeresurus okinavensis , in Sarcoplasmic Reticulum

Abstract

The lectin himehabu lectin (HHL) has recently been isolated from crude venom of the snake Trimeresurus okinavensis.Ca2+-electrode and fluorescent Ca2+-indicator experiments showed that HHL induced release of Ca2+ from the heavy fraction of skeletal muscle sarcoplasmic reticulum (HSR). The release of Ca2+ induced by caffeine from HSR was abolished by ryanodine, Mg2+ and ruthenium red, typical inhibitors of Ca2+-release channels, whereas that induced by HHL was only partially reduced by these inhibitors. HHL, unlike caffeine, had no effect on [3H]ryanodine binding to HSR.These results suggest that HHL induces release of Ca2+ which is at least partially mediated through Ca2+-release channels with novel pharmacological properties.