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.
Division of Biochemistry, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, England.
J R
JR
Lagnado
E
E
Kirazov
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