Calmodulin JMU: Difference between revisions

Calmodulin has a molecular mass of 16 kilodaltons (kD) and it functions along with ryanodine receptor (RyR)<ref>doi: 10.1242/jcs.133454</ref>. CaM consists of 148 amino acid residues and is characterized by a helix-loop-helix binding motif, also known as the <scene name='71/716518/Efhand/2'>EF hand</scene><ref>doi:10.1016/S0006-3495(98)77876-2</ref>. Calmodulin has one subunit with a distinct dumbbell shape in which a linker region joins two globular domains<ref>doi:10.1371/journal.pcbi.1004063</ref>. Calmodulin is known to undergo a conformational change upon binding with a calcium ion in which each lobe transitions from a closed conformation to an open conformation<ref>doi:10.1002/elps.1150110104</ref>. This protein has four major, high-affinity binding sites, as shown by figure 1. The calmodulin <scene name='71/716518/Bindingsite/1'>binding region</scene> has been shown to be a series of hydrophobic amino acids (such as Trp or Leu), hydrophilic amino acids (such as Glu or Asp), and basic amino acids (such as Arg or Lys)<ref>PMID:1737757</ref>. Calmodulin typically wraps around its target, with the two globular domains gripping either side of it (Figure 1). NMR studies clearly show that the connector between the two calcium binding globular domains is flexible even when it is not bound to its target proteins. However, the full range of flexibility can be seen in calmodulin interactions with its target proteins (Figure 1).