Mucins are extracellular large highly glycosylated molecules having mucin domains. Usually one also demands that there is more than 50% of the mass that is due to glycans. Mucin or PTS domains are found also in other extracellular proteins, but are dominating in molecules that are usually called mucins. Mucin domains are rich in the amino acids threonine, serine and proline, where the oligosaccharides are linked via N-acetylgalactosamine to the hydroxy amino acids. There are two types of mucins, secreted and membrane bound. Some of the secreted mucins are gel-forming due to their polymeric nature.
Just throwing a little mucin knowledge out there. Pass it along. Tell us what you know about them?