Role of phosphorylation in conformational adaptability of bovine myelin basic protein

Authors

  • Gladys E. Deibler,

    Corresponding author
    1. Laboratory of Cerebral Metabolism, National Institute of Mental Health, U. S. Public Health Service, Department of Health and Human Services, Bethesda, Maryland 20892
    • Laboratory of Cerebral Metabolism, National Institute of Mental Health, 9000 Roekville Pike, Building 36, Room 1A05, Bethesda, MD 20892
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  • Audrey L. Stone,

    1. Laboratory of Cell Biology, National Institute of Mental Health, U. S. Public Health Service, Department of Health and Human Services, Bethesda, Maryland 20892
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  • Marian W. Kies

    1. Laboratory of Cerebral Metabolism, National Institute of Mental Health, U. S. Public Health Service, Department of Health and Human Services, Bethesda, Maryland 20892
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Abstract

Controlled thrombic digestion of a preparation of components 2 + 3 isolated from the 18.5 kDa bovine myelin basic protein (MBP) yielded a polypeptide that was monophosphorylated on threonine 97 (component 3pT97). This is the first posttranslationally phosphorylated MBP isolated in pure form. We studied the effect of this single phosphate on the conformational adaptability of 18.5 kDa bovine MBP by comparing the circular dichroism (CD) spectrum of component 3pT97 with the spectra of highly purified nonphosphorylated components 1 and 2. The CD spectra of nonphosphorylated component 1 and component 2 [monodeamidated forms(s) of component1] were indistinguishable, while component 3pt97 exhibited a different spectrum. The singly phophorylated MBP component exhibited 13% more ordered conformations than that adopted by nonphosphorylated MBP in dilute aqueous solutions. This was estimated from the CD spectra, and apparently involved about 17 additional amino acid residues in β-structure(s).

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