Preparation and properties of the calmodulin-binding domain of skeletal muscle myosin light chain kinase.

Peptides corresponding to the calmodulin-binding domain of MLCK and other target enzymes promise to be useful tools in the study of calmodulin action. Not only will they help to elucidate the molecular interactions of calmodulin with specific target enzymes, but they should also prove to be useful calmodulin antagonists because of their high affinity and high specificity. Given the lack of sequence similarity in the peptides presently known to avidly bind calmodulin, it seems as likely as not that there will be little sequence homology found between calmodulin-binding domains from different calmodulin-dependent enzymes. If this is the case, it may be difficult to identify the calmodulin-binding domain of a target enzyme by simple inspection of the enzyme's sequence. However, the techniques described in this chapter require only nominal amounts of target enzyme and should, therefore, prove useful in a situation where the sequence of a target enzyme is known from DNA cloning work, but only a small quantity of pure enzyme is available for structure-function studies.