Localization of calmodulin in the enterocyte of Necturus small intestine.

Calmodulin was localized in the small intestine of Necturus maculosa at both the light- and electron-microscopic levels utilizing an affinity-purified, monospecific antibody and immunoperoxidase cytochemistry. The microvilli and basolateral membranes of the epithelium were highly reactive, the cytoplasm was moderately reactive. Connective tissue, endothelia, and muscularis of the submucosa were also reactive. The mitochondrial matrix, nuclear envelope, and terminal web, and mucous granules of goblet cells were unreactive. Omission of the primary antibody, substitution of immunoglobulin not bound to the affinity column or inappropriate immunoglobulin (sheep anti-viral src product) for the primary antibody, caused no immunoreaction product to be formed.