β-Mannosidase (}, ''mannanase'', ''mannase'', ''β-
D-mannosidase'', ''β-mannoside mannohydrolase'', ''exo-β-
D-mannanase'', ''lysosomal β A mannosidase'') is an
enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
with
systematic name
A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature.
A semisystematic name or semitrivi ...
''β-
D-mannoside mannohydrolase'', which is in humans encoded by the ''MANBA''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
This enzyme
catalyses the following
chemical reaction
A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...
: Hydrolysis of terminal, non-reducing
β-D-mannose residues in β-
D-mannosides
This gene encodes a member of the
glycosyl hydrolase 2 family. The encoded protein localizes to the
lysosome
A lysosome () is a membrane-bound organelle that is found in all mammalian cells, with the exception of red blood cells (erythrocytes). There are normally hundreds of lysosomes in the cytosol, where they function as the cell’s degradation cent ...
where it is the final
exoglycosidase
Exoglycosidases are glycoside hydrolase enzymes that cleave the glycosidic linkage of a terminal monosaccharide in an oligosaccharide or polysaccharide. Because each residue is removed separately, a series of exoglycosidases, each one cleaving at ...
in the pathway for
''N''-linked glycoprotein oligosaccharide
An oligosaccharide (; ) is a carbohydrate, saccharide polymer containing a small number (typically three to ten) of monosaccharides (simple sugars). Oligosaccharides can have many functions including Cell–cell recognition, cell recognition and ce ...
catabolism. Mutations in this gene are associated with
β-mannosidosis, a
lysosomal storage disease
Lysosomal storage diseases (LSDs; ) are a group of over 70 rare inherited metabolic disorders that result from defects in lysosomal function. Lysosomes are sacs of enzymes within cells that digest large molecules and pass the fragments on to other ...
that has a wide spectrum of neurological involvement.
References
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External links
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EC 3.2.1
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