Calmodulin is a mediator of the effects of calcium ions in living systems, particularly in the process of skeletal muscle contraction. Calmodulin is a low molecular weight, acidic, calcium binding protein which mediates the Ca2+ regulation of a wide range of physiological processes throughout eukaryotic organisms. At low free Ca2+ concentrations, such that exist in resting muscle sarcoplasm, calmodulin exists in the Ca2+-free form in which state it does not generally interact with a target protein. Following an appropriate stimulus, the free Ca2+ concentration rises whereupon Ca2+ binds to calmodulin which undergoes a conformational change enabling it to interact with a target protein or proteins. The overall result of this protein-protein interaction is a physiological effect, e.g., Ca2+ binding to calmodulin in smooth muscle allows it to interact with and activate myosin light chain kinase which catalyzes the phosphorylation of myosin. This reaction results in contraction of the smooth muscle.  Calmodulin in the Ca2+ is in control of three enzymes in skeletal muscle: phosphorylase kinase, myosin light chain kinase and a protein kinase of the sarcoplasmic reticulum.

Biotinylation is the process of covalently attaching biotin to a protein, nucleic acid or other molecule. In this case biotin is covalently bond to porcine brain derived calmodulin. Biotinylated calmodulins offer several advantages as probes of protein-protein interactions. Useful in the study of calmodulin-binding protein expression, physical points of calmodulin-target interaction, and proteolytic mapping of related calmodulin-binding protein.

Calmodulin-dependent control of cellular functions has stemmed from identification of the calmodulin-binding proteins, which are activated by Ca2+-calmodulin. Biotinylated porcine brain calmodulin using NHS ester activated biotin with an 8 atom spacer arm.

Additional Information

Additional Information