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Open Access item Circular dichroism analysis of ligand-induced conformational changes in protein kinase C. Mechanism of translocation of the enzyme from the cytosol to the membranes and its implications

Authors:Boscá, Lisardo
Morán, Federico
Issue Date:1993
Publisher:Portland Press
Citation:Biochemical Journal 290(3): 827-832 (1993)
Abstract:The structural changes following the binding to protein kinase C (PKC) of activators that promote its translocation to lipid environments were studied by far-u.v. c.d. and intrinsic fluorescence measurements of the protein. In the absence of activators, PKC contained 40% alpha-helix, with an average size of 13 amino acids per alpha-helix segment, and 12% beta-structure as deduced from c.d. spectral analysis while fitting a set of model proteins of known structure. Ligands that promote translocation and activation of the enzyme, such as Ca2+ ions and phorbol esters, produced drastic changes in the c.d. spectra which may be interpreted as a reduction in the average number of consecutive amino acids in the alpha-helix. Most of the total alpha-helix structure was conserved and an increase in beta-structure was produced by active phorbol esters. These activators differentially affected the fluorescence of PKC: phorbol esters shifted the emission maximum to the red, whereas Ca2+ produced a marked decrease in the intensity of the fluorescence emission, suggesting in both cases that tryptophan residues were exposed to increased polar environments after binding of the ligands.
Description:6 pages, 6 figures, 1 table.
Publisher version (URL):http://www.biochemj.org/bj/290/bj2900827.htm
Appears in Collections:(IIBM) Artículos

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