Cathepsin F 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 ''CTSF''
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 ba ...
.
Cysteine cathepsin
Papain-like proteases (or papain-like (cysteine) peptidases; abbreviated PLP or PLCP) are a large protein family of cysteine protease enzymes that share protein structure, structural and catalytic mechanism, enzymatic properties with the group's n ...
s are a
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
of
cysteine protease
Cysteine proteases, also known as thiol proteases, are hydrolase enzymes that degrade proteins. These proteases share a common catalytic mechanism that involves a nucleophilic cysteine thiol in a catalytic triad or dyad.
Discovered by Gopal Chund ...
s that represent a major component of the
lysosomal
A lysosome () is a membrane-bound organelle found in many animal Cell (biology), cells. They are spherical Vesicle (biology and chemistry), vesicles that contain Hydrolysis, hydrolytic enzymes that can break down many kinds of biomolecules. A ly ...
proteolytic system. In general,
cathepsin
Cathepsins (Ancient Greek ''kata-'' "down" and ''hepsein'' "boil"; abbreviated CTS) are proteases ( enzymes that degrade proteins) found in all animals as well as other organisms. There are approximately a dozen members of this family, which are d ...
s contain a
signal peptide
A signal peptide (sometimes referred to as signal sequence, targeting signal, localization signal, localization sequence, transit peptide, leader sequence or leader peptide) is a short peptide (usually 16-30 amino acids long) present at the N-ter ...
, followed by a
propeptide
A protein precursor, also called a pro-protein or pro-peptide, is an inactive protein (or peptide) that can be turned into an active form by post-translational modification, such as breaking off a piece of the molecule or adding on another molecule ...
and then a catalytically active mature region. The very long (251-amino acid residues) proregion of the cathepsin F precursor contains a
C-terminal
The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is ...
domain similar to the pro-segment of
Cathepsin L-like enzymes, a 50-residue flexible linker peptide, and an
N-terminal
The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the ami ...
domain predicted to adopt a
cystatin
The cystatins are a family of cysteine protease inhibitors which share a sequence homology and a common tertiary structure of an alpha helix lying on top of an anti-parallel beta sheet. The family is subdivided as described below.
Cystatins sho ...
-like fold. The cathepsin F proregion is unique within the papain family cysteine proteases in that it contains this additional N-terminal segment predicted to share structural similarities with cysteine protease inhibitors of the cystatin superfamily. This cystatin-like domain contains some of the elements known to be important for inhibitory activity. CTSF encodes a predicted protein of 484 amino acids that contains a 19-residue signal peptide. Cathepsin F contains five potential
N-glycosylation
''N''-linked glycosylation, is the attachment of an oligosaccharide, a carbohydrate consisting of several sugar molecules, sometimes also referred to as glycan, to a nitrogen atom (the amide nitrogen of an asparagine (Asn) residue of a protein), ...
sites, and it may be targeted to the endosomal/lysosomal compartment via the
mannose 6-phosphate receptor
The mannose 6-phosphate receptors (MPRs) are transmembrane glycoproteins that target enzymes to lysosomes in vertebrates.
Mannose 6-phosphate receptors bind newly synthesized lysosomal hydrolases in the trans-Golgi network (TGN) and deliver th ...
pathway. The cathepsin F gene is ubiquitously expressed, and it maps to chromosome 11q13, close to the gene encoding
cathepsin W
Cathepsin W is a protein that in humans is encoded by the ''CTSW'' gene.
The protein encoded by this gene, a member of the peptidase C1 family of cysteine cathepsins, is a cysteine protease cathepsin that may have a specific function in the mecha ...
.
Immunodiagnostics of ''Opisthorchis viverrini''
Cathepsin F can be used as an alternative way to test for the disease known as
Opisthorchis Viverrini
''Opisthorchis viverrini'', common name Southeast Asian liver fluke, is a food-borne trematode parasite from the family Opisthorchiidae that infects the bile duct. People are infected after eating raw or undercooked fish. Infection with the par ...
. In recent years, the diagnosis of Opisthorchis Viverrini has been done by stool examination and is considered to be the "gold standard" method. However, stool based diagnosis can be unreliable although it is a non-invasive method. Experiments preformed showed that by using
Recombinant DNA
Recombinant DNA (rDNA) molecules are DNA molecules formed by laboratory methods of genetic recombination (such as molecular cloning) that bring together genetic material from multiple sources, creating sequences that would not otherwise be foun ...
techniques with Cathepsin F cysteine protease, can create far more reliable results.
Expression of Cathepsin F in Yesso Scallop (''Mizuhopecten yessoensis'')
Recent experiments has shown the discovery of Cathepsin F in Yesso scallop (''
Mizuhopecten yessoensis
''Mizuhopecten yessoensis'' (Yesso scallop, giant Ezo scallop) is a species of marine bivalve mollusks in the family Pectinidae, the scallops. Its name Yesso/Ezo refers to its being found north of Japan.
Its tissues bioaccumulate algal yesso ...
'').
The identification of the Cathepsin F gene in various embryonic developmental stages of the Yesso Scallop has major importance. The Cathepsin F gene has an important role in the innate immune response. The Yesso Scallop has been suffering from high mortality due to bacterial diseases. The discovery of Cathepsin F can lead to farther research and a solution to the Yesso Scallop mortality problem.
References
Further reading
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External links
* The
MEROPS
MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibitor ...
online database for peptidases and their inhibitors
C01.018
Proteases
EC 3.4.22
Cathepsins
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