@article{130426,
  keywords = {Animals, Models, Molecular, Kinetics, Protein Structure, Tertiary, Neurons, Molecular Sequence Data, Binding Sites, Time Factors, Recombinant Fusion Proteins, Amino Acid Sequence, Green Fluorescent Proteins, Mice, Calcium, Drosophila melanogaster, Acoustic Stimulation, Auditory Perception, Calmodulin},
  author = {Xiaonan Sun and Aleksandra Badura and Diego Pacheco and Laura Lynch and Eve Schneider and Matthew Taylor and Ian Hogue and Lynn Enquist and Mala Murthy and Samuel Wang},
  title = {Fast GCaMPs for improved tracking of neuronal activity},
  abstract = { The use of genetically encodable calcium indicator proteins to monitor neuronal activity is hampered by slow response times and a narrow Ca(2+)-sensitive range. Here we identify three performance-limiting features of GCaMP3, a popular genetically encodable calcium indicator protein. First, we find that affinity is regulated by the calmodulin domain{\textquoteright}s Ca(2+)-chelating residues. Second, we find that off-responses to Ca(2+) are rate-limited by dissociation of the RS20 domain from calmodulin{\textquoteright}s hydrophobic pocket. Third, we find that on-responses are limited by fast binding to the N-lobe at high Ca(2+) and by slow binding to the C-lobe at lower Ca(2+). We develop Fast-GCaMPs, which have up to 20-fold accelerated off-responses and show that they have a 200-fold range of K(D), allowing coexpression of multiple variants to span an expanded range of Ca(2+) concentrations. Finally, we show that Fast-GCaMPs track natural song in Drosophila auditory neurons and generate rapid responses in mammalian neurons, supporting the utility of our approach. },
  year = {2013},
  journal = {Nat Commun},
  volume = {4},
  pages = {2170},
  issn = {2041-1723},
  doi = {10.1038/ncomms3170},
  language = {eng},
}