Direct incorporation of GDP into microtubules without GTP hydrolysis

Conference · Fri May 01 00:00:00 EDT 1987 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:6026794

Lin, C M; Hamel, E

Tubulin bearing (8-/sup 14/C)GDP in the exchangeable nucleotide binding site was prepared, and its polymerization was examined with microtubule-associated proteins containing minimal nucleoside diphosphate kinase and nonspecific phosphatase contamination. Although microtubule assembly required GTP, significant incorporation of tubulin-bound GDP into microtubules without exchange of the radiolabeled GDP for GTP was observed under reaction conditions which favored an increased proportion of tubulin x GDP relative to tubulin x GTP. These were low GTP concentrations, low Mg/sup 2 +/ concentrations, high tubulin concentrations, and exogenous GDP in the reaction mixture. The minimum tubulin x GTP:tubulin x GDP ratio required for microtubule assembly was determined to establish the relative importance of the two tubulin species in the initiation of assembly and was found to be about 2:1. In addition, the relative efficiency with which tubulin x GTP and tubulin x GDP were incorporated into microtubules was determined. They found that tubulin x GDP was incorporated into polymer about half as efficiently as tubulin x GTP.

• Research Organization: National Cancer Institute, Bethesda, MD
• OSTI ID: 6026794
• Report Number(s): CONF-870644-; TRN: 87-037299
• Journal Information: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 46:6; Conference: 78. annual meeting of the American Society of Biological Chemists conference, Philadelphia, PA, USA, 7 Jun 1987
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
NUCLEOTIDES
METABOLISM
CARBON 14 COMPOUNDS
GUANYLIC ACID
MICROTUBULES
PHOSPHATASES
PHOSPHOTRANSFERASES
POLYMERIZATION
PROTEINS
TRACER TECHNIQUES
CELL CONSTITUENTS
CHEMICAL REACTIONS
ENZYMES
ESTERASES
HYDROLASES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
ORGANIC COMPOUNDS
PHOSPHORUS-GROUP TRANSFERASES
TRANSFERASES
550501* - Metabolism- Tracer Techniques