Direct incorporation of GDP into microtubules without GTP hydrolysis

Conference · Fri May 01 04:00:00 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-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 46:6
• Country of Publication: United States
• Language: English

Related Subjects

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