Mucin 3A

Mucin 3A (MUC3A) is a human gene that encodes a transmembrane mucin protein. This protein is a member of the mucin family, which are high-molecular-weight glycoproteins characterized by a large number of O-linked oligosaccharides attached to a protein core. These heavily glycosylated proteins are secreted by epithelial cells and form a protective and lubricating barrier on mucosal surfaces.

MUC3A, specifically, is a type I transmembrane protein, meaning it spans the cell membrane with a single pass. Its structure consists of a large extracellular domain containing a variable number of tandem repeats (VNTRs) rich in serine and threonine residues, which are the sites for O-glycosylation. This extracellular region is heavily glycosylated, giving the protein its characteristic properties. It also possesses a cytoplasmic tail involved in signaling.

MUC3A is expressed in various epithelial tissues, including the gastrointestinal tract (such as the small intestine and colon), respiratory tract, and conjunctiva. It plays a role in protecting these surfaces from pathogens, mechanical stress, and dehydration. The mucin layer formed by MUC3A and other mucins acts as a barrier preventing direct contact of harmful substances with the underlying epithelial cells.

While the precise functions of MUC3A are still being investigated, research suggests its involvement in cell signaling, cell adhesion, and epithelial cell differentiation. Alterations in MUC3A expression or glycosylation patterns have been implicated in various diseases, including inflammatory bowel disease (IBD), cystic fibrosis, and certain types of cancer. Studies continue to explore the specific roles of MUC3A in these conditions and its potential as a therapeutic target.