Calmodulin

Calmodulin, a ubiquitous eukaryotic calcium binding protein, is a principal mediator of the calcium signal. It participates in signalling pathways inducing proliferation, motility and cell cycle progression. Human calmodulin is encoded by three genes CALM1, CALM2 and CALM3 located on different chromosomes. The vertebrate CALM family of genes is unique in that its members specify an identical protein. The protein itself is made up of 148 amino acids and has four calcium binding domains. As calmodulin is essential for normal cell function, it is likely that levels are tightly controlled both temporally and spatially. Immunohistochemical staining for calmodulin has been reported in the epithelia of testis, breast, stomach, prostate, gall bladder as well as in macrophages, fibroblasts and sebaceous glands within the dermis of skin. In healing skin wounds, calmodulin is found at its highest levels in maturing keratinocytes. It is noticeably abundant in epidermis close to a wound and re-epithelializing margins where calcium levels are highest. In studies of Alzheimer's brains, calmodulin immunostaining has been reported to be lost in cortical regions where large amounts of aluminium have accumulated.

Image: Calmodulin staining of situ ductal carcinoma of human breast. Note cytoplasmic and membrane staining of malignant cells. Paraffin section.