Human MUC-1 Alexa Fluor™ Plus 555-conjugated Antibody

MUC-1 (Mucin-1; also episialin, MAM-6, PEM and PUM) is a 150-450 kDa type I transmembrane glycoprotein that belongs to the Mucin family of molecules. It forms a protective barrier against microbes on the apical surface of most glandular epithelium, and becomes prominently displayed on tumor cells. Mature human MUC-1 is 1232 amino acids (aa) in length. It contains an 1135 aa extracellular domain (ECD) (aa 24-1158), and a signal transducing 73 aa cytoplasmic tail (aa 1182-1255). The ECD is highly polymorphic as evidenced by a highly variable number of 20 aa O-glycosylated tandem repeats. Intracellular processing cleaves MUC-1 between Gly1097 and Ser1098, generating a noncovalently linked heterodimer that is expressed on the cell surface. The C-terminus is 22-25 kDa in size, while the N-terminus is highly variable (70-400 kDa in size), a function of the number of resident tandem repeats. Cell surface processing by TACE releases a soluble ECD fragment of variable MW. There are multiple splice variants that show massive reductions in the size of the ECD. Over aa 126-145, human MUC-1 shares < 50% aa identity with mouse MUC-1. When compared to human, mouse MUC-1 is found not to be polymorphic and possess poorly conserved tandem repeat sequences.