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Fast-Response Calmodulin-Based Fluorescent Indicators Reveal Rapid Intracellular Calcium Dynamics

Helassa, N; Zhang, X H; Conte, IL; Scaringi, J; Esposito, E; Bradley, J; Carter, T; Ogden, D; Morad, M (2015) Fast-Response Calmodulin-Based Fluorescent Indicators Reveal Rapid Intracellular Calcium Dynamics. Scientific Reports, 5. ISSN 2045-2322
SGUL Authors: Carter, Thomas David

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Faithful reporting of temporal patterns of intracellular Ca 2 + dynamics requires the working range of indicators to match the signals. Current genetically encoded calmodulin-based fluorescent indicators are likely to distort fast Ca 2 + signals by apparent saturation and integration due to their limiting fluorescence rise and decay kinetics. A series of probes was engineered with a range of Ca 2 + affinities and accelerated kinetics by weakening the Ca 2 + -calmodulin-peptide interactions. At 37 °C, the GCaMP3-derived probe termed GCaMP3 fast is 40-fold faster than GCaMP3 with Ca 2 + decay and rise times, t 1/2 , of 3.3 ms and 0.9 ms, respectively, making it the fastest to-date. GCaMP3 fast revealed discreet transients with significantly faster Ca 2 + dynamics in neonatal cardiac myocytes than GCaMP6f. With 5-fold increased two-photon fluorescence cross-section for Ca 2 + at 940 nm, GCaMP3 fast is suitable for deep tissue studies. The green fluorescent protein serves as a reporter providing important novel insights into the kinetic mechanism of target recognition by calmodulin. Our strategy to match the probe to the signal by tuning the affinity and hence the Ca 2 + kinetics of the indicator is applicable to the emerging new generations of calmodulin-based probes

Item Type: Article
Additional Information: This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit
SGUL Research Institute / Research Centre: Academic Structure > Molecular and Clinical Sciences Research Institute (MCS)
Academic Structure > Molecular and Clinical Sciences Research Institute (MCS) > Cell Sciences (INCCCS)
Journal or Publication Title: Scientific Reports
Article Number: 15978
ISSN: 2045-2322
3 November 2015Published
Publisher License: Creative Commons: Attribution 4.0
Project IDFunderFunder ID
094385/Z/10/ZWellcome Trust
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