These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Ca2+-dependent binding of [3H]calmodulin to the microsomal fraction of brain.
    Author: Sobue K, Morimoto K, Kanda K, Kakiuchi S.
    Journal: J Biochem; 1982 Apr; 91(4):1313-20. PubMed ID: 7096288.
    Abstract:
    The binding of calmodulin to a brain microsomal fraction rich in synaptic membranes and vesicles was studied using 3H-labeled calmodulin. The binding was Ca2+-dependent and highly specific to calmodulin since it was competitively displaced only by unlabeled calmodulin and not by 200-4,000-fold excess of other proteins that included troponin-C and S-100 protein. Within the physiological pH range, the specific binding, defined as the amount of bound [3H]calmodulin which is displacable by the addition of an excess of unlabeled calmodulin, agreed well with the Ca2+-dependent binding defined as the difference between the total binding in the presence of Ca2+ and the binding obtained with EGTA in place of Ca2+. Both binding activities appeared to be greatest at about pH 7.0. The binding, either specific or Ca2+-dependent, is a calmodulin concentration-dependent saturable process. The dose-dependent curve obtained for increasing concentrations of [3H]calmodulin agreed well with that obtained for mixtures of a fixed concentration of [3H]calmodulin and increasing concentrations of unlabeled calmodulin over the entire concentration range examined. The results serve as the basis for using [3H]calmodulin in binding studies. Scatchard plot analysis of the curve gave two different Kd values for calmodulin, 8.2 X 10(-8) and 5.3 X 10(-7) M. The corresponding maximum binding capacities were 1.0 X 10(14) and 1.6 X 10(14) calmodulin molecules per mg of microsomal protein, respectively. The binding ability of the microsomal fraction was completely abolished by prior treatment with proteolytic enzymes.
    [Abstract] [Full Text] [Related] [New Search]