Cathepsin X (, ''cathepsin B2'', ''cysteine-type carboxypeptidase'', ''cathepsin IV'', ''cathepsin Z'', ''acid carboxypeptidase'', ''lysosomal carboxypeptidase B'') is an
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...
.
This enzyme
catalyses the following
chemical reaction
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and break ...
: Release of
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 ...
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
residues with broad specificity, but lacks action on C-terminal
proline. Shows weak
endopeptidase
Endopeptidase or endoproteinase are proteolytic peptidases that break peptide bonds of nonterminal amino acids (i.e. within the molecule), in contrast to exopeptidases, which break peptide bonds from end-pieces of terminal amino acids. For this ...
activity
Cathepsin X is a
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 structural and enzymatic properties with the group's namesake member, papain. They are fou ...
, a
lysosomal
A lysosome () is a membrane-bound organelle found in many animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane pr ...
cysteine peptidase
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 Chun ...
of family C1 (
papain
Papain, also known as papaya proteinase I, is a cysteine protease () enzyme present in papaya (''Carica papaya'') and mountain papaya (''Vasconcellea cundinamarcensis''). It is the namesake member of the papain-like protease family.
It has wi ...
family).
See also
*
Cathepsin Z
Cathepsin Z, also called cathepsin X or cathepsin P, is a protein that in humans is encoded by the ''CTSZ'' gene.
It is a member of the cysteine cathepsin family of cysteine proteases, which has 11 members. As one of the 11 cathepsins, cathepsin ...
References
External links
*
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EC 3.4.18