Phosphorylation in vivo of chick brain microtubule-associated phospholipids.
Microtubules were prepared by temperature-dependent cycles of assembly/disassembly from chick brain labeled in vivo with 32Pi and the distribution of labeled phospholipids extracted from cold-insoluble and soluble microtubular protein fractions was analyzed by thin-layer and paper chromatography. While 32P-labeling was associated with all of the phospholipids identified after 2-D TLC, it was found that all of the relatively high radioactivity associated with phosphatidylserine (PS) was in fact associated with a minor co-migrating component which was subsequently identified as phosphatidylinositol(PI) by three independent separation procedures. It was estimated that the relative specific radioactivity in PI was several-fold higher than that associated with other microtubule-associated phospholipids. Additional experiments, in which the protein components of once-cycled microtubules were fractionated by gel permeation chromatography, provided evidence that the 36S component containing ring-like tubulin oligomers (36S) appears to be selectively associated with phospholipid components that were specifically enriched in 32P-PI. The possible significance of these findings is discussed in relation to the effects of phospholipids on microtubule dynamics and to the function of microtubules in their interactions with membranes.
Lagnado
J R
JR
Division of Biochemistry, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, England.
Kirazov
E
E
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002645:Chickens; D002855:Chromatography, Thin Layer; D008870:Microtubules / Q000378:metabolism*; D010743:Phospholipids / Q000302:isolation & purification / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism
D010743:Phospholipids; D010761:Phosphorus Radioisotopes; D014404:Tubulin