식물세포에서 분리한 Tonoplast Vesicle 에서의 Ca2+ 수송과 Inositol 1 , 4 , 5 - trisphosphate ( IP 3 ) 의 작용 = Action of Inositol 1 , 4 , 5 - trisphosphate in vitro transport of Ca2+ inisolated tonoplast vesicles

다국어 초록 (Multilingual Abstract)

Auxin may exert its effects through Ca^(2+) as a secondary messenger. To test this hypothesis, effects of auxin on Ca^(2+) release from isolated tonoplast vesicles was investigated. Tonoplast vesicles were isolated from red beet roots(Beta vulgaris L.) by metrizamide discontinuous density-gradient centrifugation. Uptake of ^(45)Ca^(2+) into tonoplast vesicles was ATP-dependent, and was blocked by calcium entry blockers such as Diltiazem, Verapamil, Flunarizin. Auxin did not induce the release of ^(45)Ca^(2+) from tonoplast vesicles preloaded with the cations, but Inositol 1,4,5-trisphosphate (IP₃) did. The IP₃ induced ^(45)Ca^(2+) release was dependent on IP₃ concentration, and was blocked by the Ca^(2+) antagonist, 8-(N,N-diethylamino)-octyl 3,4,5-trimethoxybenzoate-HCl (TMB-8). Auxin is known to generate transient change in levels of Inositol 1,4,5-trisphosphate (IP₃) and Inositol bis-phosphate (ptdIns(4,5)P₂) within minutes in Catharanthus roseus (Ettlinger, et al., 1988). These results indicate that auxin cannot alter cytoplasmic calcium levels directly but through the IP₃ secondary messenger system.