Phosphorylation of phosphatidylinositol by transverse tubule vesicles and its possible role in excitation-contraction coupling

• Published in: FEBS letters 1986-06, Vol.202 (1), p.69-73
• Main Authors: Hidalgo, Cecilia, Carrasco, M.Angélica, Magendzo, Karin, Jaimovich, Enrique
• Format: Article
• Language: English
• Subjects: (Frog skeletal muscle) Transverse tubule Lipidphosphorylation Phosphatidylinositol Excitation-contraction coupling; (Frog skeletal muscle)Transverse tubuleLipidphosphorylationPhosphatidylinositolExcitation-contraction coupling; Animals; Anura; Biological and medical sciences; Cell physiology; E-C coupling, excitation-contraction coupling; Fundamental and applied biological sciences. Psychology; In Vitro Techniques; InsP3, inositol 1,4,5-trisphosphate; Magnesium - physiology; Molecular and cellular biology; Muscle Contraction; Muscles - metabolism; Phosphatidylinositol 4,5-Diphosphate; Phosphatidylinositol Phosphates; Phosphatidylinositols - biosynthesis; Phosphatidylinositols - metabolism; Phosphatidylinositols - physiology; Phosphorylation; PtdIns 4-P, phosphatidylinositol 4-phosphate; PtdIns, phosphatidylinositol; Ptdlns 4,5-P2, phosphatidylinositol 4,5-bisphosphate; Sarcoplasmic Reticulum - metabolism; SR, sarcoplasmic reticulum; T-tubule, transverse tubule; Tetracaine - pharmacology
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(86)80651-2

Phosphorylation of phosphatidylinositol to phosphatidylinositol 4-monophosphate and to phosphatidyl-inositol 4,5-bisphosphate was demonstrated in transverse-tubule membranes isolated from frog skeletal muscle using [γ- 32P]ATP as substrate. At millimolar concentrations of Mg 2+ both phosphorylation reactions were completed within 15 s at 25°C. Isolated sarcoplasmic reticulum vesicles phosphorylated phosphatidyl-inositol to phosphatidylinositol 4-phosphate with a lower specific activity than the transverse tubules, and lacked the ability to produce phosphatidylinositol 4,5-bisphosphate. These findings show, for the first time, that isolated transverse-tubule membranes carry out one of the steps required to sustain a role for inositol trisphosphate as the physiological messenger in excitation-contraction coupling in skeletal muscle. The finding that 0.5 mM tetracaine apparently inhibits the phosphorylation of phosphatidylinositol 4-phosphate to phosphatidylinositol 4,5-bisphosphate also supports a role for these intermediates in excitation-contraction coupling.