Modulation of microtubule assembly and stability by phosphatidylinositol action on microtubule-associated protein-2

• Published in: The Journal of biological chemistry Vol. 262; no. 7; pp. 3369 - 3375
• Main Authors: Yamauchi, P.S., Purich, D.L.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 05.03.1987; American Society for Biochemistry and Molecular Biology
• Subjects: Alkaloids - pharmacology; Animals; Biological and medical sciences; brain; Brain - ultrastructure; Cattle; Cell structures and functions; Cytoskeleton, cytoplasm. Intracellular movements; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; Glycerol - pharmacology; microtubule-associated protein 2; Microtubule-Associated Proteins - antagonists & inhibitors; Microtubule-Associated Proteins - metabolism; microtubules; Microtubules - drug effects; Microtubules - metabolism; Molecular and cellular biology; Paclitaxel; Phosphatidylinositols - pharmacology; phosphoinositides; Phospholipids - pharmacology; Phosphatidylinositol; Stability; Bovine; Molecular assembly; Animal; Cytoskeleton; Microtubule associated protein; Microtubule
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)61512-1

Exposure of elongating (or assembled) bovine brain microtubules to phosphatidylinositol leads to polymerization arrest (or disassembly). The efficiency of phosphatidylinositol far exceeds the action of related phospholipids including phosphatidylethanolamine, phosphatidylcholine, 1,2-diacylglycerol, phosphatidylserine, phosphatidylglycerol, or phosphatidic acid. Phosphatidylinositol increases the apparent critical concentration for assembly, and the inhibitory effect of phosphatidylinositol on polymerization is reversed at higher concentrations of microtubule-associated proteins (MAP)s. Taxol- and glycerol-treated microtubules are insensitive to the destabilizing action of phosphatidylinositol; centrifugation and subsequent gel electrophoresis of such samples revealed that both MAP-2a and MAP-2b were selectively desorbed. Likewise, the desorption of MAP-2 was visualized by indirect immunofluorescence microscopy using primary antibodies directed toward tubulin and MAP-2. The instability of microtubules exposed to phosphatidylinositol appears to be related to the MAP-2 content.