Mucin-5B (MUC-5B) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
that in humans is encoded by the ''MUC5B''
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ...
and by ''Muc5b''
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ...
in mouse. It is one of the five gel-forming
mucins
Mucins () are a family of high molecular weight, heavily glycosylated proteins (glycoconjugates) produced by epithelial tissues in most animals. Mucins' key characteristic is their ability to form gels; therefore they are a key component in most ...
. MUC-5B can be found in whole saliva, normal lung mucus, and cervical mucus. In some diseases such as
COPD
Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by long-term respiratory symptoms and airflow limitation. The main symptoms include shortness of breath and a cough, which may or may not produce ...
, chronic rhinosinusitis (CRS), and
H. pylori-associated gastric disease.
Synthesis
All mucins are synthesized in secretory cells known, dependent on the tissue they are located in, as
goblet cell
Goblet cells are simple columnar epithelial cells that secrete gel-forming mucins, like mucin 5AC. The goblet cells mainly use the merocrine method of secretion, secreting vesicles into a duct, but may use apocrine methods, budding off their secre ...
s or mucous cells. Their creation, while still not completely understood, begins in the endoplasmic reticulum. From there, the Golgi apparatus build the O-linked glycans found in mucins. Finally, they are packaged into secretory granules.
References
05B
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