title: Stathmin: a tubulin-sequestering protein which forms a ternary T2S complex with two tubulin molecules.
abstract: Stathmin is an important regulatory protein thought to control the dynamics of microtubules through the cell cycle in a phosphorylation-dependent manner. Here we show that stathmin interacts with two molecules of dimeric alphabeta-tubulin to form a tight ternary T2S complex, sedimenting at 7.7 S. This complex appears in slow association-dissociation equilibrium in the analytical ultracentrifuge. The T2S complex is formed under a variety of ionic conditions, either from GTP- or GDP-tubulin or from the tubulin-colchicine complex. The S16/25/38/63E mutated stathmin in contrast is in rapid equilibrium with tubulin in the T2S complex. The T2S complex cannot polymerize in microtubules nor in ring oligomers. Stathmin acts as a pure tubulin-sequestering protein via formation of the T2S complex. It does not act directly on microtubule ends to promote catastrophe nor enhance microtubule dynamics.
authors.affiliation: Dynamique du cytosquelette, Laboratoire d'Enzymologie et Biochimie structurales, CNRS, 91198 Gif-sur-Yvette, France.
authors.forename: L
authors.initials: L
authors.lastname: Jourdain
authors.forename: P
authors.initials: P
authors.lastname: Curmi
authors.forename: A
authors.initials: A
authors.lastname: Sobel
authors.forename: D
authors.initials: D
authors.lastname: Pantaloni
authors.forename: M F
authors.initials: MF
authors.lastname: Carlier
mesh_terms: D000818:Animals; D019281:Dimerization; D008868:Microtubule Proteins; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D050777:Stathmin; D014404:Tubulin / Q000737:chemistry* / Q000378:metabolism; D014461:Ultracentrifugation
chemical_list: D008868:Microtubule Proteins; D010750:Phosphoproteins; D050777:Stathmin; D014404:Tubulin