Constitutively active mutants CAMs

Receptors that remain in the activated state even in the absence of ligand are often known as constitutively active mutants (CAMs). The resulting disruptions in rhodopsin signaling also often result in alterations in the phosphorylation of rhodopsin by rhodopsin kinase (GRKl), the specialized GRK enzyme expressed in the retina that is largely responsible for rapidly desensitizing the receptor when it is exposed to light. 

The gene encoding the pj-adrenergic receptor displays a fair degree of polymorphism in the human population. Like the dopamine receptors, the p -adrenergic receptor variants are often relevant to pharmacogenetics. Constitutively active mutant (CAM) and loss-of-function (LOF) variants are in evidence. 

The present chapter focuses on the physiological functions of the CaMK cascade that have been identified to date. The definition of these functions has relied heavily on the use of pharmacological inhibitors, overexpression of constitutively active or dominant/negative mutants of the various CaM kinases, and a variey of model organisms that include mice, worms and fungi null (or transgenic) for specific members of the CaMK cascade. 

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