کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10926584 1091894 2005 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Dominant affectors in the calmodulin network shape the time courses of target responses in the cell
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی بیولوژی سلول
پیش نمایش صفحه اول مقاله
Dominant affectors in the calmodulin network shape the time courses of target responses in the cell
چکیده انگلیسی
In endothelial cells nitric oxide synthase is a dominant affector in the calmodulin network by virtue of its ability to bind a significant fraction of limiting intracellular calmodulin. We have investigated how this affector function influences the kinetics of calmodulin-dependent signaling in cells co-expressing the synthase and a fluorescent calmodulin target analog similar in its interactions with calmodulin to myosin light chain kinase. The synthase binds (Ca2+)4-calmodulin with a Kd value of ∼0.2 nM and an association rate constant of ∼1.5 × 105 M−1 s−1. These values are, respectively, 10- and 100-fold smaller than the corresponding values for the analog. Thus, when Ca2+ is added to a mixture of calmodulin, target analog and synthase in vitro a large fluorescence transient with a relaxation time of ∼600 s is observed as (Ca2+)4-calmodulin is rapidly bound to the analog and then slowly captured by the higher affinity synthase. A rapid increase in the free Ca2+ concentration elicits similar transient analog responses in cells expressing the cytoplasmic target analog and either a wild-type membrane bound or mutant cytoplasmic synthase. Transient responses are not observed in cells co-expressing the fluorescent analog and a mutant T497D synthase unable to bind calmodulin. These results demonstrate that dominant affectors in the calmodulin network shape both the magnitudes and time courses of target responses in the cell.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Cell Calcium - Volume 37, Issue 6, June 2005, Pages 541-553
نویسندگان
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