Dephosphorylation of tubulin-bound guanosine triphosphate during microtubule assembly.
1. Tubulin purified from porcine brain in the presence of GTP contained 0.16 mole of GDP and 0.73 mole of GTP per 60,000 g of protein. 2. Microtubules reconstituted from the purified tubulin contained 0.43 mole of GDP and 0.41 mole of GTP per 60,000 g of protein. Guanine nucleotide bound to the exchangeable site of tubulin was converted to GDP during microtubule assembly, while GTP at the non-exchangeable site remained intact. 3. Guanine nucleotide which had been bound to the exchangeable site of tubulin before microtubule assembly was also exchangeable during disassembly.
D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism*; D046911:Macromolecular Substances; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D011485:Protein Binding; D014404:Tubulin / Q000378:metabolism*
D006023:Glycoproteins; D006150:Guanine Nucleotides; D046911:Macromolecular Substances; D014404:Tubulin; D006160:Guanosine Triphosphate