Related Experiment Video
Updated: Aug 15, 2026
Examining the Conformational Dynamics of Membrane Proteins in situ with Site-directed Fluorescence Labeling
Published on: May 29, 2011
Time-resolved fluorescence anisotropy studies show domain-specific interactions of calmodulin with IQ target
Peter Bayley1, Stephen Martin, Peter Browne
1Division of Physical Biochemistry, National Institute for Medical Research, Mill Hill, London, NW7 1AA, UK. pbayley@nimr.mrc.ac.uk
Abstract:
Single cysteine mutants of calmodulin, Cam(S38C) and Cam(N111C), have been specifically labelled with Alexa488 maleimide to study the effects of calcium on the structural dynamics of calmodulin complexed with IQ3, IQ4 and IQ34 target peptide motifs of mouse unconventional myosin-V. Using phase fluorometry, the time-resolved anisotropy shows well-separated global and segmental correlation times. The calcium-sensitive global motion of either calmodulin domain can be independently monitored in domain-specific interactions of either apo- or Ca(4).calmodulin with IQ3 or IQ4 peptides. C-domain interactions predominate, and apo-N-domain interactions are unexpectedly weak. The 1:1 complex of Ca(4).calmodulin with IQ34 behaves as a compact globular species. The results demonstrate novel dynamic aspects of calmodulin-IQ interactions relating to the calcium regulation of motility of unconventional myosin.
