6434 Biochemistry zyxwvu 1982, 21, 6434-6440 \ zyxwvu 4. 11 4 - INACTIVE . - b ACTIVE FIGURE 7: Model for reconstitution of urea-denatured glucose-6- phosphate dehydrogenase. The completely unfolded, urea-denatured monomers are shown at the extreme left. For rate constants see Table zyxwvuts 11. 25 OC. A comparison between the rate constants shows k2 Our results imply that in vivo assembly of L. mesenteroides glucose-6-phosphate dehydrogenase is not dependent on the presence of specific ligands but that the concentrations of glucose 6-phosphate, ?$AD+, and NADP+ in the cell may influence the rate o; this process. References Bartholmes, P., & Jaenicke, R. (1978) Eur. zyxwvutsrq J. Biochem. 87, Bell, J. E. (1981) in Spectroscopy in Biochemistry, Vol. 1, pp Cornish-Bowden, A., & Eisenthal, R. (1978) Biochim. Bio- Creighton, T. E. (1978) Prog. Biophys. Mol. Biol. 33, Deal, W. C., Jr. (1969) Biochemistry 8, 2795-2805. > k3' > k3" > k3. 563-567. 155-194, CRC Co., Cleveland, OH. phys. Acta 523, 268-272. 23 1-297. Eisenthal, R., & Cornish-Bowden, A. (1974) Biochem. J. 139, Gabriel, 0. (1971) Methods Enzymol. 22, 565-578. Grossman, S. H., Pyle, J., & Steiner, R. J. (1981) Biochem- Haghighi, B., & Levy, H. R. (1982) Biochemistry (second Haghighi, B., Flynn, T. G., & Levy, H. R. (1982) Biochem- Hedrick, J. L., & Smith, A. J. (1968) Arch. Biochem. Biophys. Ishaque, A., Milhausen, M., & Levy, H. R. (1974) Biochem. Jaenicke, R. (1978) Naturwissenschaften 65, 569-577. Jaenicke, R., Rudolph, R., & Heider, I. (1979) Biochemistry Kawaguchi, A., & Bloch, K. (1974) J. Biol. Chem. 249, Krebs, H., Rudolph, R., & Jaenicke, R. (1 979) Eur. J. Bio- Milhausen, M. (1974) Ph.D. Dissertation, Syracuse University. Muhlrad, A,, Hegyi, G., & Horanvi, M. (1969) Biochim. Olive, C., & Levy, H. R. (1971) J. Biol. Chem. 246, Rudolph, R., & Jaenicke, R. (1976) Eur. J. Biochem. 63, Rudolph, R., Gerschitz, J., & Jaenicke, R. (1978) Eur. J. Teipel, J., & Koshland, D. E., Jr. (1971a) Biochemistry zy 10, Teipel, J., & Koshland, D. E., Jr. (1 97 1 b) Biochemistry IO, Wetlaufer, D. B., & Ristow, S. (1973) Annu. Rev. Biochem. Wood, D. C., Jurgensen, S. R., Geesin, J. C., & Harrison, J. Zamenhof, S. (1957) Methods Enzymol. 3, 696-704. 7 15-720. istry 20, 6122-6128. paper of three in this issue). istry (first paper of three in this issue). 126, 155-164. Biophys. Res. Commun. 59, 894-901. 18, 1217-1223. 5793-5800. chem. 100, 359-364. Biophys. Acta 181, 184-1 90. 2043-2046. 409-4 1 7. Biochem. 87, 601-606. 792-798. 798-805. 42, 135-158. H. (1981) J. Biol. Chem. 256, 2377-2382. Reversibility of Coated Vesicle Dissociation? P. K. Nandi, K. Prasad, R. E. Lippoldt, A. Alfsen, and H. Edelhoch* ABSTRACT: The dissociation of the coated vesicles to clathrin and uncoated vesicles and their reassociation have been studied under various conditions. The extent of reassociation is pH dependent and increases slightly with increasing concentrations of the components. Unlike the self-association of clathrin which is strongly salt dependent, the reassociation of clathrin and uncoated vesicles is practically independent of salt con- centration. The coated vesicle gradually loses its coat with increasing pH, and the dissociation process is not an all or none reaction. Ca2+inhibits dissociation of the coated vesicles and enhances the reassociation of clathrin and uncoated vesicles. Our results show that, although many conditions result in reassociation of protein and lipid vesicle, few conditions result in vesicles of both the same size and composition as native coated vesicles. C o a t e d pits and vesicles are involved in receptor-mediated endocytosis (Goldstein et al., 1979; OcMeford & Whyte, 1977; Pearse, 1980), secretion of glycoproteins (Rothman et al., 1980), and membrane exchange (Heuser & Reese, 1973). From the Clinical Endocrinology Branch, National Institute of Ar- thritis, Diabetes, and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20205. Received June zyxwvutsrq 4, 1982. Clathrin is readily dissociated from coated vesicles (CV)' by various methods which are mild enough not to cause denatu- ration, i.e., elevated pH, 2 M urea, and 0.50 M Tris (Pearse, 1975; Shook et al., 1979; Keen et al., 1979; Woodward & CV, coated vesicle(s); Mes, 2-(N-morpholino)- ethanesulfonic acid; DPH, 1,6-diphenyl- 1,3,5-hexatriene; Tris, tris(hy- droxymethy1)aminomethane; NaDodSO,, sodium dodecyl sulfate. ' Abbreviations: This article not subject to US. Copyright. Published 1982 by the American Chemical Society