title: Evidence that a polysaccharide from the cortex of sea urchin egg inhibits microtubule assembly through its binding to microtubule-associated proteins.
abstract: A new factor that not only inhibits brain microtubule assembly but also causes depolymerization of pre-assembled microtubules was purified from unfertilized sea urchin egg cortices. The purified fraction contained neither proteins nor nucleic acids. The inhibitory activity of the fraction was heat-stable and insensitive to various proteases, but decrease on treatment with glycosidases or with periodic acid. The purified factor was identified as a polysaccharide by analysis of the sugar composition. The sedimentation constant of the factor was estimated to be 9S by sucrose density gradient centrifugation. Polyacrylamide gel electrophoresis of the factor revealed a single broad band stained with periodic acid-Schiff reagent. The factor completely inhibited microtubule assembly at a factor: microtubule protein ratio of 0.03 (w/w). The polysaccharide was found to bind to microtubule-associated proteins, thereby inhibiting microtubule assembly.
mesh_terms: D000818:Animals; D002499:Centrifugation, Density Gradient; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D008869:Microtubule-Associated Proteins; D008870:Microtubules / Q000187:drug effects*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010063:Ovum / Q000032:analysis*; D011134:Polysaccharides / Q000302:isolation & purification / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism*; D012617:Sea Urchins; D014404:Tubulin / Q000378:metabolism*
chemical_list: D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D011134:Polysaccharides; D011506:Proteins; D014404:Tubulin