title: Tubulin domains responsible for assembly of dimers and protofilaments.
abstract: The protein domains responsible for the dimerization and polymerization of tubulin have been determined using chemical cross-linking and limited proteolysis. The intra-dimer bond is formed by the N-terminal domain of alpha-tubulin and the C-terminal domain of beta-tubulin. Conversely, the inter-dimer bond along protofilaments is formed by the N-terminal domain of beta-tubulin (carrying the exchangeable GTP) and the C-terminal domain of alpha-tubulin. The domains of proteolytically cleaved tubulin remain tightly associated in solution. Apart from the monomer, tubulin shows three levels of assembly: the dimer, oligomer and polymer. Several oligomeric species can be visualized by electron microscopy of rotary shadowed phosphocellulose-tubulin, h.p.l.c. and non-denaturing gel electrophoresis. Tubulin's capacity to form the higher level aggregates is not destroyed by enzymatic nicking.
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005990:Glycerol; D006160:Guanosine Triphosphate / Q000378:metabolism; D046911:Macromolecular Substances; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure*; D008961:Models, Structural; D013552:Swine; D014404:Tubulin / Q000378:metabolism*
chemical_list: D046911:Macromolecular Substances; D014404:Tubulin; D006160:Guanosine Triphosphate; D005990:Glycerol