Does the inositol tris/tetrakisphosphate pathway exist in rat heart?

FEBS Letters

Poggioli, J.¹  Renard, D.¹ 

[1] Unité de Recherches de Physiologie et Pharmacologie Cellulaire, INSERM U-274, Université Paris-Sud (Bât. 443), F-91405 Orsay Cedex, France

关键词: Inositol trisphosphate;    Inositol tetrakisphosphate;    Ca2+;    (Rat heart);   

DOI  :  10.1016/0014-5793(87)81254-1

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Appearance of two isomers of inositol trisphosphate (InsP₃) was observed when [³H]inositol prelabelled rat heart ventricles were stimulated for 10 and 30 s with noradrenaline. In contrast, inositol tetrakisphosphate (InsP₄) could not be detected. However the existence of the inositol tris/tetrakisphosphate pathway was demonstrated by studying [³H]inositol 1,4,5-trisphosphate (Ins-1,4,5-P₃) metabolism in a soluble fraction of rat heart. There, [³H]Ins-1,4,5-P₃ was phosphorylated to form [³H]Ins-1,3,4,5-P₄. Raising [Ca²⁺] from 1 nM to 1, μM increased InsP₃ kinase activity by 2-fold (EC₅₀ for Ca²⁺ approx. 56 nM). This effect appeared to be due to an increase of the apparent V _max of the enzyme while the apparent K _m was unchanged.

【 授权许可】

Unknown