Characterization of the microtubule-activated ATPase of brain cytoplasmic dynein (MAP 1C)
Document Type
Journal ArticlePublication Date
1988-09-01Keywords
Adenosine Triphosphatases; Animals; Brain; Centrifugation, Density Gradient; Cytosol; Dynein ATPase; Microtubule-Associated Proteins; Microtubules; Oxidation-Reduction; Potassium Chloride; Substrate Specificity; TubulinLife Sciences
Medicine and Health Sciences
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We recently found that the brain cytosolic microtubule-associated protein 1C (MAP 1C) is a microtubule-activated ATPase, capable of translocating microtubules in vitro in the direction corresponding to retrograde transport. (Paschal, B. M., H. S. Shpetner, and R. B. Vallee. 1987b. J. Cell Biol. 105:1273-1282; Paschal, B. M., and R. B. Vallee. 1987. Nature [Lond.]. 330:181-183.). Biochemical analysis of this protein (op. cit.) as well as scanning transmission electron microscopy revealed that MAP 1C is a brain cytoplasmic form of the ciliary and flagellar ATPase dynein (Vallee, R. B., J. S. Wall, B. M. Paschal, and H. S. Shpetner. 1988. Nature [Lond.]. 332:561-563). We have now characterized the ATPase activity of the brain enzyme in detail. We found that microtubule activation required polymeric tubulin and saturated with increasing tubulin concentration. The maximum activity at saturating tubulin (Vmax) varied from 186 to 239 nmol/min per mg. At low ionic strength, the Km for microtubules was 0.16 mg/ml tubulin, substantially lower than that previously reported for axonemal dynein. The microtubule-stimulated activity was extremely sensitive to changes in ionic strength and sulfhydryl oxidation state, both of which primarily affected the microtubule concentrations required for half-maximal activation. In a number of respects the brain dynein was enzymatically similar to both axonemal and egg dyneins. Thus, the ATPase required divalent cations, calcium stimulating activity less effectively than magnesium. The MgATPase was inhibited by metavandate (Ki = 5-10 microM for the microtubule-stimulated activity), 1 mM NEM, and 1 mM EHNA. In contrast to other dyneins, the brain enzyme hydrolyzed CTP, TTP, and GTP at higher rates than ATP. Thus, the enzymological properties of the brain cytoplasmic dynein are clearly related to those of other dyneins, though the brain enzyme is unique in its substrate specificity and in its high sensitivity to stimulation by microtubules.Source
J Cell Biol. 1988 Sep;107(3):1001-9.
DOI
10.1083/jcb.107.3.1001Permanent Link to this Item
http://hdl.handle.net/20.500.14038/32548PubMed ID
2971069Related Resources
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http://creativecommons.org/licenses/by-sa/4.0/ae974a485f413a2113503eed53cd6c53
10.1083/jcb.107.3.1001
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