Figure 1.

Calcium-activated myristoyl switch of recoverin. At low intracellular concentrations of calcium ions, the myristoyl group of recoverin is hidden inside the N-terminal domain of the protein (left). When the concentration of calcium rises, two of the four evolutionarily conserved EF hand motifs (top) each bind a calcium ion and the protein undergoes a conformational transition exposing the myristoyl group, as well as opening up a binding site for RK (right). The calcium-loaded recoverin is capable of reversible membrane binding to rod outer segment (ROS) disk membranes. The protein structures shown in this figure were determined by solution NMR^7,8 (PDB IDs 1IKU and 1JSA). The last 13 C-terminal amino acid residues are missing from the structures as their geometry was not resolved in the NMR experiments.