Mucin

Mucin is a type of protein that is produced by the epithelial tissues and is a major component of mucus. It plays a crucial role in the body's defense mechanism by forming a protective barrier against pathogens and foreign particles. Mucin is also involved in cell signaling and adhesion.

Structure

Mucins are high molecular weight glycoproteins, composed of a protein core and oligosaccharide side chains. The protein core is rich in serine and threonine, which are sites for O-glycosylation. The oligosaccharide side chains are attached to the protein core through O-glycosidic bonds.

Function

Mucins serve several functions in the body. They form a protective barrier on the epithelial surfaces, preventing the entry of pathogens and foreign particles. They also lubricate these surfaces, facilitating the movement of materials through the body's passages. In addition, mucins are involved in cell signaling and adhesion, playing a role in various physiological processes.

Types

There are two main types of mucins: secreted mucins and membrane-bound mucins. Secreted mucins are released by the goblet cells and form a gel-like layer on the epithelial surfaces. Membrane-bound mucins are attached to the cell membrane and contribute to the formation of the glycocalyx.

Clinical significance

Abnormalities in mucin production or structure can lead to various diseases. For example, overproduction of mucin is a characteristic feature of cystic fibrosis, a genetic disorder that affects the lungs and digestive system. On the other hand, deficiencies in mucin can result in dryness of the eyes and mouth, as seen in Sjögren's syndrome.

See also

• Glycoprotein
• Goblet cell
• Cystic fibrosis
• Sjögren's syndrome

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