Investigation of the structure and dynamic of calmodulin-nitric oxide synthase complexes using NMR spectroscopy.

NMR spectroscopy allows for the determination of high resolution structures, as well as being an efficient method for studying the dynamics of protein-protein and protein-peptide complexes. N relaxation and H/D exchange experiments allow for the analysis of these structural dynamics at a residue specific level. Calmodulin (CaM) is a small cytosolic Ca binding protein that serves as a control element for many enzymes.

Calmodulin regulates Ca3 T-type channels at their gating brake.

Calcium (Ca1 and Ca2) and sodium channels possess homologous CaM-binding motifs, known as IQ motifs in their C termini, which associate with calmodulin (CaM), a universal calcium sensor. Ca3 T-type channels, which serve as pacemakers of the mammalian brain and heart, lack a C-terminal IQ motif. We illustrate that T-type channels associate with CaM using co-immunoprecipitation experiments and single particle cryo-electron microscopy.