''Inactive ubiquitin carboxyl-terminal hydrolase 53'' is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

that in humans is encoded by the ''USP53''

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 ...

. Although USP53 is classified as a

deubiquitinating enzyme Deubiquitinating enzymes (DUBs), also known as deubiquitinating peptidases, deubiquitinating isopeptidases, deubiquitinases, ubiquitin proteases, ubiquitin hydrolases, or ubiquitin isopeptidases, are a large group of proteases that cleave ubiquiti ...

based on sequence homology to other

proteases A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do ...

from this group, it lacks a functionally essential histidine in the catalytic domaine and activity assays suggest that USP53 is catalytically inactive. Even though USP53 is devoid of catalytic activity, USP53 serves important physiological functions: mutations in ''Usp53'' have been shown to cause progressive hearing loss in mice, as well as late-onset hearing loss and

cholestasis Cholestasis is a condition where the flow of bile from the liver to the duodenum is impaired. The two basic distinctions are: * obstructive type of cholestasis, where there is a mechanical blockage in the duct system that can occur from a gallston ...

in humans. USP53 localizes at cellular

tight junctions Tight junctions, also known as occluding junctions or ''zonulae occludentes'' (singular, ''zonula occludens''), are multiprotein junctional complexes between epithelial cells, sealing and preventing leakage of solutes and water. They also play a ...

and interacts with

tight junction protein 2 Tight junction protein ZO-2 is a protein that in humans is encoded by the ''TJP2'' gene. Tight junction proteins (TJPs) belong to a family of membrane-associated guanylate kinase (MAGUK) homologs that are involved in the organization of epithelia ...

(TJP2). Mutations in ''TJP2'' have also been shown to cause hearing impairments and cholestasis.

References

Further reading