Sialidase-1, is a mammalian lysosomal
neuraminidase
Exo-α-sialidase (, sialidase, neuraminidase; systematic name acetylneuraminyl hydrolase) is a glycoside hydrolase that cleaves the glycosidic linkages of neuraminic acids:
: Hydrolysis of α-(2→3)-, α-(2→6)-, α-(2→8)- glycosidic linkag ...
enzyme which in humans is encoded by the ''NEU1''
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 ...
.
Function
The protein SIALIDASE-1 encoded by the NEU-1 gene encodes the lysosomal enzyme SIALIDASE-1, which cleaves terminal
sialic acid
Sialic acids are a class of alpha-keto acid sugars with a nine-carbon backbone.
The term "sialic acid" () was first introduced by Swedish biochemist Gunnar Blix in 1952. The most common member of this group is ''N''-acetylneuraminic acid ...
residues from substrates such as
glycoproteins
Glycoproteins are proteins which contain oligosaccharide (sugar) chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known a ...
and
glycolipids
Glycolipids () are lipids with a carbohydrate attached by a glycosidic (covalent) bond. Their role is to maintain the stability of the cell membrane and to facilitate cellular recognition, which is crucial to the immune response and in the co ...
. In 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 ...
, this enzyme is part of a heterotrimeric complex together with beta-galactosidase and cathepsin A (the latter also referred to as 'protective protein'). Mutations in this gene can lead to
sialidosis
Mucolipidosis type I (ML I) is an inherited lysosomal storage disease that results from a deficiency of the enzyme alpha-N -acetyl neuraminidase (sialidase). The lack of this enzyme results in an abnormal accumulation of complex carbohydrates kno ...
.
Clinical significance
Mutations in ''NEU1'' leads to
sialidosis
Mucolipidosis type I (ML I) is an inherited lysosomal storage disease that results from a deficiency of the enzyme alpha-N -acetyl neuraminidase (sialidase). The lack of this enzyme results in an abnormal accumulation of complex carbohydrates kno ...
, a rare
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 ...
.
Sialidase has also been shown to enhance recovery from spinal cord contusion injury when injected in rats.
Interactions
NEU1 has been shown to
interact with
Cathepsin A
Cathepsin A is an enzyme that is classified both as a cathepsin and a carboxypeptidase. In humans, it is encoded by the ''CTSA'' gene. The enzyme is also known as Human Protective Protein. It is a lysosomal serine carboxypeptidase. The enzyme ...
.
References
Further reading
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{{Sugar hydrolases
Human proteins