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
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
بیوشیمی، ژنتیک و زیست شناسی مولکولی
بیولوژی سلول
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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 â¼0.2Â nM and an association rate constant of â¼1.5Â ÃÂ 105Â Mâ1Â sâ1. 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 â¼600Â 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
Journal: Cell Calcium - Volume 37, Issue 6, June 2005, Pages 541-553
نویسندگان
Quang-Kim Tran, D.J. Black, Anthony Persechini,