Calmodulin-Target Peptide Complex

The figure to the left shows the structure of Ca2+-CaM complexed with the CaM-binding domain peptide (P) from rabbit smooth muscle myosin light chain kinase determined by NMR spectroscopy.á Notice how the central linker domain (LD) acts as a flexible tether to allow CaM to interact with the target peptide. In this end-on view of the structure, the channel formed by CaM through which the MLCK peptide runs is lined with hydrophobic residues.á Interaction of these residues with hydrophobic amino acids in the target peptide accounts for ~80% of the contacts between CaM and MLCK. This mechanism of interaction accounts for the tremendous amino acid sequence variation in the CaM-binding domains of target proteins. This is because hydrophobic interaction can accommodate a wider number of amino acid residue interactions than charge-charge interaction can.

If you have trouble visualizing CaM-target peptide interaction from the molecular model shown in the figure, click here to see a "cartoon" version that might help.

This structure was reproduced from atomic coordinates deposited in the Brookhaven Protein Data Bank (structure code 2BBN) using the program Rasmol.

For an even better look at this structure, click here to view a model that you can rotate and manipulate based on the NMR structure of apo-calmodulin.

To view this structure, you will need to have installed Chemscape Chime or Rasmol, which are both free plug-ins for viewing molecular structures.

Copyrightę 1998 Ray Zielinski