Abstract
Amyloplasts were isolated and purified from wheat endosperm and the envelope membranes reconstituted into liposomes. Envelope membranes were solubilized in n-octyl beta-D-glucopyranoside and mixed with liposomes supplemented with 5.6 mol% cholesterol to produce proteoliposomes of defined size, which showed negligible leakage of internal substrates. Transport experiments with proteoliposomes revealed a counter-exchange of glucose 1-phosphate (Glc1P), glucose 6-phosphate (Glc6P), inorganic phosphate (Pi), 3-phosphoglycerate and dihydroxyacetone phosphate. The Glc1P/Pi counter-exchange reaction exhibited an apparent K(m) for Glc1P of 0.4 mM. Glc6P was a competitive inhibitor of Glc1P transport (Ki 0.8 mM), and the two hexose phosphates could exchange with each other, indicating the operation of a single carrier protein. Glc1P/Pi antiport in proteoliposomes showed an exchange stoichiometry at pH 8.0 of 1 mol of phosphate transported per mol of sugar phosphate.
Full Text
The Full Text of this article is available as a PDF (566.8 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Ambudkar S. V., Sonna L. A., Maloney P. C. Variable stoichiometry of phosphate-linked anion exchange in Streptococcus lactis: implications for the mechanism of sugar phosphate transport by bacteria. Proc Natl Acad Sci U S A. 1986 Jan;83(2):280–284. doi: 10.1073/pnas.83.2.280. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Borchert S., Harborth J., Schunemann D., Hoferichter P., Heldt H. W. Studies of the Enzymic Capacities and Transport Properties of Pea Root Plastids. Plant Physiol. 1993 Jan;101(1):303–312. doi: 10.1104/pp.101.1.303. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Doige C. A., Yu X., Sharom F. J. The effects of lipids and detergents on ATPase-active P-glycoprotein. Biochim Biophys Acta. 1993 Feb 23;1146(1):65–72. doi: 10.1016/0005-2736(93)90339-2. [DOI] [PubMed] [Google Scholar]
- Hutchinson F. J., Francis S. E., Lyle I. G., Jones M. N. The characterisation of liposomes with covalently attached proteins. Biochim Biophys Acta. 1989 Jan 16;978(1):17–24. doi: 10.1016/0005-2736(89)90492-6. [DOI] [PubMed] [Google Scholar]
- Jain M. K., Zakim D. The spontaneous incorporation of proteins into preformed bilayers. Biochim Biophys Acta. 1987 Apr 27;906(1):33–68. doi: 10.1016/0304-4157(87)90004-9. [DOI] [PubMed] [Google Scholar]
- Kasahara M., Hinkle P. C. Reconstitution and purification of the D-glucose transporter from human erythrocytes. J Biol Chem. 1977 Oct 25;252(20):7384–7390. [PubMed] [Google Scholar]
- Möhlmann T., Batz O., Maass U., Neuhaus H. E. Analysis of carbohydrate transport across the envelope of isolated cauliflower-bud amyloplasts. Biochem J. 1995 Apr 15;307(Pt 2):521–526. doi: 10.1042/bj3070521. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Neuhaus H. E., Batz O., Thom E., Scheibe R. Purification of highly intact plastids from various heterotrophic plant tissues: analysis of enzymic equipment and precursor dependency for starch biosynthesis. Biochem J. 1993 Dec 1;296(Pt 2):395–401. doi: 10.1042/bj2960395. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Neuhaus H. E., Henrichs G., Scheibe R. Characterization of Glucose-6-Phosphate Incorporation into Starch by Isolated Intact Cauliflower-Bud Plastids. Plant Physiol. 1993 Feb;101(2):573–578. doi: 10.1104/pp.101.2.573. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schwarz M., Gross A., Steinkamp T., Flügge U. I., Wagner R. Ion channel properties of the reconstituted chloroplast triose phosphate/phosphate translocator. J Biol Chem. 1994 Nov 25;269(47):29481–29489. [PubMed] [Google Scholar]
- Scotto A. W., Zakim D. Reconstitution of membrane proteins: catalysis by cholesterol of insertion of integral membrane proteins into preformed lipid bilayers. Biochemistry. 1986 Apr 8;25(7):1555–1561. doi: 10.1021/bi00355a015. [DOI] [PubMed] [Google Scholar]
- Urbaneja M. A., Alonso A., Gonzalez-Mañas J. M., Goñi F. M., Partearroyo M. A., Tribout M., Paredes S. Detergent solubilization of phospholipid vesicle. Effect of electric charge. Biochem J. 1990 Sep 1;270(2):305–308. doi: 10.1042/bj2700305. [DOI] [PMC free article] [PubMed] [Google Scholar]
- de la Maza A., Parra J. L. Structural phase transitions involved in the interaction of phospholipid bilayers with octyl glucoside. Eur J Biochem. 1994 Dec 15;226(3):1029–1038. doi: 10.1111/j.1432-1033.1994.t01-1-01029.x. [DOI] [PubMed] [Google Scholar]