Essais Cathepsin B

Thiol protease which is believed to participate in intracellular degradation and turnover of proteins (PubMed:12220505). Cleaves matrix extracellular phosphoglycoprotein MEPE (PubMed:12220505). Involved in the solubilization of cross-linked TG/thyroglobulin in the thyroid follicle lumen (By similarity). Has also been implicated in tumor invasion and metastasis (PubMed:3972105).

This gene encodes a member of the C1 family of peptidases. Alternative splicing of this gene results in multiple transcript variants. At least one of these variants encodes a preproprotein that is proteolytically processed to generate multiple protein products. These products include the cathepsin B light and heavy chains, which can dimerize to form the double chain form of the enzyme. This enzyme is a lysosomal cysteine protease with both endopeptidase and exopeptidase activity that may play a role in protein turnover. It is also known as amyloid precursor protein secretase and is involved in the proteolytic processing of amyloid precursor protein (APP). Incomplete proteolytic processing of APP has been suggested to be a causative factor in Alzheimer's disease, the most common cause of dementia. Overexpression of the encoded protein has been associated with esophageal adenocarcinoma and other tumors. Multiple pseudogenes of this gene have been identified.

Expressed in the stratum spinosum of the epidermis. Weak expression is detected in the stratum granulosum.

Keratolytic winter erythema: An autosomal dominant genodermatosis characterized by recurrent episodes of palmoplantar erythema and epidermal peeling presenting seasonal variation. KWE manifests during childhood. Skin lesions may spread to the dorsum of hands and feet and to the interdigital spaces. Lower legs, knees and thighs may also be involved. A less common finding is a slowly migratory, annular erythema that is seen mostly on the extremities. Between flares, the skin can appear unremarkable. Itching can occur, and hyperhidrosis, associated with a pungent odor, is invariably present. Formation of vesicles is rare, whereas keratolysis that causes the formation of dry blisters is regularly seen. Cold weather, moisture, febrile diseases, and physical and mental stress can trigger exacerbations. In severely affected individuals, skin manifestations persist unremittingly. Penetrance of the disease is high, but expressivity is variable, even within the same family.

Belongs to the peptidase C1 family.

Lysosome. Melanosome. Secreted > Extracellular space. Apical cell membrane.

Identified by mass spectrometry in melanosome fractions from stage I to stage IV (PubMed:17081065). Localizes to the lumen of thyroid follicles and to the apical membrane of thyroid epithelial cells (By similarity).