Cathepsin A is an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 which is classified both as a cathepsin

Cathepsin

Cathepsins are proteases: proteins that break apart other proteins, found in many types of cells including those in all animals. There are approximately a dozen members of this family, which are distinguished by their structure, catalytic mechanism, and which proteins they cleave...

 and a carboxypeptidase

Carboxypeptidase

A carboxypeptidase is a protease enzyme that hydrolyzes the peptide bond of an amino acid residue at the carboxy-terminal end...

. In humans, it is encoded by the CTSA gene

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

This gene encodes a glycoprotein which associates with lysosomal enzymes beta-galactosidase

Beta-galactosidase

β-galactosidase, also called beta-gal or β-gal, is a hydrolase enzyme that catalyzes the hydrolysis of β-galactosides into monosaccharides. Substrates of different β-galactosidases include ganglioside GM1, lactosylceramides, lactose, and various glycoproteins...

 and neuraminidase

Neuraminidase

Neuraminidase enzymes are glycoside hydrolase enzymes that cleave the glycosidic linkages of neuraminic acids. Neuraminidase enzymes are a large family, found in a range of organisms. The most commonly known neuraminidase is the viral neuraminidase, a drug target for the prevention of the spread...

 to form a complex of high molecular weight multimers. The formation of this complex provides a protective role for stability and activity. It is protective for β-galactosidase and neuraminidase

Neuraminidase

Neuraminidase enzymes are glycoside hydrolase enzymes that cleave the glycosidic linkages of neuraminic acids. Neuraminidase enzymes are a large family, found in a range of organisms. The most commonly known neuraminidase is the viral neuraminidase, a drug target for the prevention of the spread...

.

Clinical significance

Deficiencies in this gene are linked to multiple forms of galactosialidosis

Galactosialidosis

Galactosialidosis is a lysosomal storage disease.It is associated with cathepsin A.-External links:*...

.

Interactions

Cathepsin A has been shown to interact

Protein-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 NEU1

NEU1

Sialidase 1 , also known as NEU1 is a mammalian lysosomal neuraminidase enzyme which in humans is encoded by the NEU1 gene.- Function :...

.