Differential reactivities of lysines in calmodulin complexed to phosphatase

Calmodulin and calmodulin complexed with calcineurin phosphatase were trace labeled with [3H]acetic anhydride and the incorporation of [3H]acetate into each epsilon-amino lysine of calmodulin was measured. The relative reactivities of calmodulin lysines were higher in the presence of Ca2+ than in th...

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Bibliographic Details
Published in:The Journal of biological chemistry 1987-11, Vol.262 (32), p.15466-15471
Main Authors: Winkler, M A, Fried, V A, Merat, D L, Cheung, W Y
Format: Article
Language:English
Subjects:
Acetates - metabolism
Acetic Acid
Acetic Anhydrides - metabolism
Animals
Calcineurin
Calcium - metabolism
calmodulin
Calmodulin - metabolism
Calmodulin-Binding Proteins - metabolism
Cattle
lysine
Lysine - metabolism
phosphatase
Phosphoprotein Phosphatases - metabolism
Phosphoric Monoester Hydrolases - metabolism
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Summary:Calmodulin and calmodulin complexed with calcineurin phosphatase were trace labeled with [3H]acetic anhydride and the incorporation of [3H]acetate into each epsilon-amino lysine of calmodulin was measured. The relative reactivities of calmodulin lysines were higher in the presence of Ca2+ than in the presence of EGTA, and the order was: Lys-75 greater than Lys-94 greater than Lys-148 greater than or equal to Lys-77 greater than Lys-13 greater than or equal to Lys-21 greater than Lys-30. The changes in relative reactivity implied a change in conformation. When calmodulin was complexed with the phosphatase, Lys-21, Lys-77, and Lys-148 were most protected, implying that these residues are at or near the interaction sites or are conformationally perturbed by the interaction. Lys-30 and Lys-75 were slightly protected, lysine 13 showed no change, while lysine 94 significantly increased in reactivity. Comparison with results obtained from myosin light chain kinase using a similar technique (Jackson, A. E., Carraway, K. L., III, Puett, D., and Brew, K. (1986) J. Biol. Chem. 261, 12226-12232) reveals that calmodulin may interact with each of the two enzymes similarly at or near Lys-21, Lys-75, and Lys-148; one difference with phosphatase is that complex formation also involved Lys-77. These findings suggest that calmodulin interacts differently with its target enzymes.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)47749-6