Cathepsin B
Encyclopedia
Cathepsin B is an enzymatic protein belonging to the peptidase (or protease) families. In humans, it is coded by the CTSB gene
.
cysteine protease
composed of a dimer of disulfide-linked heavy and light chains, both produced from a single protein precursor. It is a member of the peptidase C1 family. At least five transcript variants encoding the same protein have been found for this gene.
into the amyloid plaques
found in Alzheimer's disease
patients. However, this function is now known to be mediated by BACE1 protease. It is now thought that cathepsin B can degrade β-amyloid precursor protein into harmless fragments. Thus, it is conceivable cathepsin B may play a pivotal role in the natural defense against Alzheimer's disease. Overexpression of cathepsin B has been associated with esophageal adenocarcinoma and other tumors.
Mutations in the CTSB gene have been linked to tropical pancreatitis, a form of chronic pancreatitis
.
with cystatin B
, S100A10
and cystatin A
.
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
.
Function
The protein encoded by this gene is a lysosomalLysosome
thumb|350px|Schematic of typical animal cell, showing subcellular components. [[Organelle]]s: [[nucleoli]] [[cell nucleus|nucleus]] [[ribosomes]] [[vesicle |vesicle]] rough [[endoplasmic reticulum]]...
cysteine protease
Cysteine protease
Proteases are enzymes that degrade polypeptides. Cysteine proteases have a common catalytic mechanism that involves a nucleophilic cysteine thiol in a catalytic dyad. The first step is deprotonation of a thiol in the enzyme's active site by an adjacent amino acid with a basic side chain, usually a...
composed of a dimer of disulfide-linked heavy and light chains, both produced from a single protein precursor. It is a member of the peptidase C1 family. At least five transcript variants encoding the same protein have been found for this gene.
Clinical significance
Cathepsin B was once suspected as a candidate protease participating in the conversion of β-amyloid precursor proteinAmyloid precursor protein
Amyloid precursor protein is an integral membrane protein expressed in many tissues and concentrated in the synapses of neurons. Its primary function is not known, though it has been implicated as a regulator of synapse formation, neural plasticity and iron export...
into the amyloid plaques
Amyloid
Amyloids are insoluble fibrous protein aggregates sharing specific structural traits. Abnormal accumulation of amyloid in organs may lead to amyloidosis, and may play a role in various neurodegenerative diseases.-Definition:...
found in Alzheimer's disease
Alzheimer's disease
Alzheimer's disease also known in medical literature as Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death...
patients. However, this function is now known to be mediated by BACE1 protease. It is now thought that cathepsin B can degrade β-amyloid precursor protein into harmless fragments. Thus, it is conceivable cathepsin B may play a pivotal role in the natural defense against Alzheimer's disease. Overexpression of cathepsin B has been associated with esophageal adenocarcinoma and other tumors.
Mutations in the CTSB gene have been linked to tropical pancreatitis, a form of chronic pancreatitis
Chronic pancreatitis
Chronic pancreatitis is a long-standing inflammation of the pancreas that alters its normal structure and functions. It can present as episodes of acute inflammation in a previously injured pancreas, or as chronic damage with persistent pain or malabsorption....
.
Interactions
Cathepsin B has been shown to interactProtein-protein interaction
Protein–protein interactions occur when two or more proteins bind together, often to carry out their biological function. Many of the most important molecular processes in the cell such as DNA replication are carried out by large molecular machines that are built from a large number of protein...
with cystatin B
Cystatin B
Cystatin-B is a protein that in humans is encoded by the CSTB gene.-Interactions:Cystatin B has been shown to interact with Cathepsin B.-External Links:* * The MEROPS online database for peptidases and their inhibitors:...
, S100A10
S100A10
S100-A10, also known as p11, is a protein that is encoded by the S100A10 gene in humans and the S100a10 gene in other species. S100-A10 is a member of the S100 family of proteins containing two EF-hand calcium-binding motifs. S100 proteins are localized in the cytoplasm and/or nucleus of a wide...
and cystatin A
Cystatin A
Cystatin-A is a protein that in humans is encoded by the CSTA gene.-Interactions:Cystatin A has been shown to interact with Cathepsin B and CTSL1.-External Links:* The MEROPS online database for peptidases and their inhibitors:...
.
External links
- The MEROPSMeropsMerops may refer to:* Merops , a genus of bee-eaters.* MEROPS, an on-line database for peptidases.It may also refer to several figures from Greek mythology:* King of Ethiopia, husband of Clymene, who lay with Helios and bore Phaethon...
online database for peptidases and their inhibitors: C01.060