The HMPV monoclonal antibody specifically binds to CD227 which is also known as Mucin-1 (MUC1). A major form of CD227 is expressed as a type I transmembrane glycoprotein. CD227 belongs to the epithelial mucin family whose members are heavily O-glycosylated and characterized by high molecular weight, and an amino acid composition rich in serine, threonine, proline, and glycine. CD227 is variably expressed on the surfaces of normal and malignant glandular and ductal epithelial cells, and some hematopoietic cell lineages including subsets of T cells, B cells, monocytes and dendritic cells. Soluble forms of CD227 may arise by shedding from the cell surface or by secretion of forms derived from alternative RNA splicing. The HMPV antibody binds to the core peptide of the MUC1 protein. The core protein contains a domain of 20 amino-acid tandem repeats which function as multiple epitopes for this monoclonal antibody. Incomplete glycosylation of some tumor-associated mucins may lead to variable unmasking of the multiple peptide epitopes leading to the observed differences in immunostaining intensities between cells from normal and malignant tissues. CD227 plays roles in the provision of protective barrier function, the regulation of cellular adhesion, and the transduction of multiple signal pathways.
The antibody was conjugated to BD Horizon Red 718, which has been developed exclusively for BD Biosciences as a better alternative to Alexa Fluor® 700. BD Horizon Red 718 can be excited by the red laser (628 – 640 nm) and, with an Em Max around 718 nm, it can be detected using a 730/45 nm filter. Due to similar excitation and emission properties, we do not recommend using R718 in combination with APC-R700 or Alexa Fluor® 700.