Abstract
The insertion of soluble proteins into membranes has been a topic of considerable interest. We have studied the insertion of bovineα-lactalbumin into single-bilayer vesicles prepared from egg phosphatidylcholine (PC). Fluoresence studies indicated rapid and tight binding of apo-α-lactalbumin (apo-α-LA) to PC vesicles as a function of pH. The binding was maximal at pH values which favor the formation of the molten globule state. As an increase of hydrophobic surface is observed in the molten globule state, this conformational state can provide a molecular basis for insertion of soluble proteins into membranes. The membrane-bound complex formed at low pH (3.0) could be isolated and was found to be stable at neutral pH. The structural characterization of the apo-α-LA-PC complex was studied by fluorescence quenching using iodide, acrylamide, and 9,10-dibromostearic acid. The results obtained indicated that some of the tryptophans of apo-α-LA were buried in the membrane interior and some were exposed on the outer side. Fluorescence quenching and CD studies indicated the membrane-bound conformation of apo-α-LA was some conformational state that is between the soluble, fully folded conformation and the molten globule state.
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Abbreviations
- PC:
-
phosphatidyl choline
- α-LA:
-
α-lactalbumin
- DML:
-
dimyristoyl phosphatidyl choline
References
Alexandrescu, A. T., Evans, P. A., Pitkeathly, M., Baum, J., and Dobson, C. M. (1993).Biochemistry 32, 1707–1718.
Ames, B. N. (1986).Meth. Enzymol. 5, 115–119.
Baum, J., Dobson, C. M., Evans, P. A., and Hanley, C. (1989).Biochemistry 28, 7–13.
Berliner, L. J., and Koga, K. (1987).Biochemistry 26, 3006–3009.
Burstein, E. A., Vedenkina, N. S., and Ivkova, M. N. (1973).Photochem. Photobiol. 18, 263–279.
Bychkova, V. E., Pain, R. H., and Ptitsyn, O. B. (1988).FEBS 238, 231–234.
Chyan, C.-L., Wormald, C., Dobson, C. M., Evans, P. A., and Baum, J. (1993).Biochemistry 32, 5681–5691.
De Foresta, B., Le Maire, M., Orlowski, S., Champell, P., Lund, S., Moller, J. V., Michelangeli, F., and Lee, A. G. (1989).Biochemistry 28, 2558–2567.
Eftink, M. R., and Ghiron, C. A. (1976).Biochemistry 15, 672.
Ellis, R. J., and vander Vies, S. M. (1991).Annu. Rev. Biochem. 60, 321–347.
Hanssens, I., van Cuenebroeck, J. C., Pottel, H., Preaux, G., and Cauwelaert, F. V. (1985).Biochem. Biophys. Acta 817, 154–164.
Hanssens, I., Houthuys, C., Herreman, W., and van Cauwelaert, F. H. (1980).Biochem. Biophys. Acta 602, 539–557.
Hartl, F. U., and Neupert, W. (1990).Science 247, 930–937.
Hurtley, S. M. (1993).Trends Biochem. Sci. 18, 453–455.
Kim, J., and Kim, H. (1986).Biochemistry 25, 7864–7871.
Kim, J., and Kim, H. (1989).Biochim. Biophys. Acta 983, 1–8.
Koga, K., and Berliner, J. (1985).Biochemistry 24, 7257–7262.
Kronman, M. J. (1989).Crit. Rev. Biochem. Mol. Biol. 24, 565–667.
Kuwajima, K. (1989).Proteins 6, 87–103.
Laemmli, U. K. (1970).Nature 227, 680–685.
Lala, A. K., and Kaul, P. (1992).J. Biol. Chem. 267, 19914–19918.
Lala, A. K., and Koppaka, V. (1989).Photochem. Photobiol. 449, 763–767.
Lehrer, S. S. (1971).Biochemistry 10, 3254–3263.
Martin, J., Langer, T., Boteva, R., Schramel, A., Horvich, A. L., and Hartl, F. U. (1991).Nature 352, 36–42.
Muga, A., Gonzalez-Manas, J. M., Lakey, J. H., Pattus, F., and Surewicz, W. K. (1993).J. Biol. Chem. 268, 1553–1557.
Musci, G., and Berliner, L. J. (1985).Biochemistry 24, 3852–3856.
Neville, D. M., Jr., and Hudson, T. H. (1986).Annu. Rev. Biochem. 55, 195–224.
Parker, C. A. (1968).Photoluminescence of Solutions, Elsevier, New York, pp. 220–222.
Ptitsyn, O. B. (1987).J. Protein Chem. 6, 273–293.
Robbins, F. M., and Holmes, L. G. (1970).Biochem. Biophys. Acta 221, 234–240.
Rothman, J. E., and Orci, L. (1992).Nature 355, 409–415.
Rothman, J. E., Miller, R. L., and Urbani, L. J. (1984).J. Cell Biol. 99, 260–271.
Stem, O., and Volmer, M. (1919).Z. Phys. 20, 183–188.
VanDael, H., and VanCauwelaert, F. (1988).Biochim. Biophys. Acta 943, 126–136.
Van der Goot, F. G., Gonzalez-Manas, J. M., Lakey, J. H., and Pattus, F. (1991).Nature 354, 408–410.
Zhao, J. M., and London, E. (1988).J. Biol. Chem. 263, 15369–15377.
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Lala, A.K., Kaul, P. & Ratnam, P.B. Membrane-protein interaction and the molten globule state: Interaction of α-lactalbumin with membranes. J Protein Chem 14, 601–609 (1995). https://doi.org/10.1007/BF01886886
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DOI: https://doi.org/10.1007/BF01886886