Antibodies to the cytoplasmic domain of the MUC1 mucin show conservation throughout mammals.

An antiserum against the carboxy-terminal seventeen amino acids of the human MUC1 mucin has been raised and extensively characterized. This antiserum, CT1, immunoprecipitates two high molecular weight polymorphic bands (greater than 200 kDa) from a metabolically labelled breast cancer cell line corresponding to the two alleles which have previously been shown to contain different numbers of a twenty amino acid repeat. The CT1 antiserum reacted with tissues from many mammalian species and immunoprecipitated large polymorphic proteins, suggesting that the cytoplasmic portion of the molecule is well conserved. The cell and tissue distribution of Muc-1 mucin in the mouse has been studied by immunocytochemistry. This protein is abundant at the apical surfaces of epithelial tissues and is found expressed in the stomach, kidney, mammary gland, pancreas, salivary gland, lung, trachea, uterus, cervix and vagina.