Interaction of tubulin with phospholipid vesicles. II. Physical changes of the protein

We have shown that soluble tubulin will bind to small unilamellar vesicles of dipalmitoyl phosphatidylcholine (Klausner, R. D., Kumar, N., Weinstein, J. N., Blumenthal, R., and Flavin, M. (1981) J. Biol. Chem. 256, 5879-5885). This association uniquely occurs at the lipid phase transition. The tubul...

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Bibliographic Details
Published in:The Journal of biological chemistry 1981-06, Vol.256 (11), p.5886-5889
Main Authors: Kumar, N, Klausner, R D, Weinstein, J N, Blumenthal, R, Flavin, M
Format: Article
Language:English
Subjects:
Acrylamides
Animals
Brain
C.D
Cattle
conformation
dipalmitoyl phosphatidylcholine
fluorescence
Liposomes
Macromolecular Substances
Protein Binding
Protein Conformation
Pulmonary Surfactants
Spectrometry, Fluorescence
tryptophan
Tryptophan - analysis
Tubulin
vesicles
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Summary:We have shown that soluble tubulin will bind to small unilamellar vesicles of dipalmitoyl phosphatidylcholine (Klausner, R. D., Kumar, N., Weinstein, J. N., Blumenthal, R., and Flavin, M. (1981) J. Biol. Chem. 256, 5879-5885). This association uniquely occurs at the lipid phase transition. The tubulin, when bound to the vesicles, displays an altered tryptophan fluorescence characterized by a 5-nm blue shift in the emission maximum and a 22% decrease in fluorescence intensity, when compared to soluble tubulin. Tryptophans in vesicle-bound tubulin are less accessible to the aqueous collisional quenchers, acrylamide and iodide, than in soluble tubulin. Circular dichroism studies reveal an increase in alpha-helical content of tubulin as a result of vesicle interaction. Proteolytic digestion by trypsin of vesicle bound tubulin is slower than of soluble tubulin. The beta subunit of tubulin is preferentially protected from trypsin by vesicle interaction. Furthermore, the pattern of tryptic cleavage products is altered by this interaction.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(19)69291-4