Other Enzymes

D-Tyrosyl-tRNA Deacylase 1 (DTD1) is a member of the DTD family. DTD1 hydrolyzes D-tyrosyl-tRNA(Tyr) into D-tyrosine and free tRNA(Tyr). DTD1 may be a defense mechanism against a damaging effect of D-tyrosine. DTD1 is an ATPase involved in DNA replication, which may facilitate loading of CDC45 onto pre-replication complexes. The DTD1 protein localizes to the DUE (DNA unwinding elements) of active replication origins. DTD1 is expressed in numerous adult and fetal tissues, with the highest levels in the testis, ovary, spleen and in the adult and fetal brain. DTD1 might be a risk factor for AIA (aspirin-intolerant asthma) by catalyzing the hydrolysis of D-tryptophan and interacting with the tyrosyl-tRNA synthetase (tyrRS) enzyme that promotes a pro-inflammatory phenotype.

ARG2 participates in the regulation of extra-urea cycle arginine metabolism and also in down-regulation of nitric oxide synthesis. Extrahepatic arginase functions to regulate L-arginine bioavailability to NO synthase. Since NO synthase is found in the penile corpus cavernosum smooth muscle, the clitoral corpus cavernosum and the vagina, ARG2 takes part in both male and female sexual arousal and therefore a potential target for the treatment of male and female sexual arousal disorders.

Arginase-1 is part of the urea cycle, it catalyzes the hydrolysis of arginine to ornithine and urea. There are two isoforms of mammalian arginase which differ in their tissue location, subcellular localization, immunologic crossreactivity & physiologic role. Arginase-1is a cytosolic enzyme and expressed primarily in the liver tissue. Inherited deficiency in this enzyme may lead toargininemia, which is an autosomal recessive disease in which hyperammonemia is detected.

ARG1 catalyzes the hydrolysis of arginine to ornithine and urea. 2 isoforms of mammalian arginase exist which vary in their tissue distribution, subcellular localization, immunologic crossreactivity and physiologic role. ARG1 is a cytosolic enzyme and expressed widely in the liver as part of the urea cycle. Inherited deficiency of this ARG1 causes argininemia, which is an autosomal recessive disorder characterized by hyperammonemia.

HTATIP2 is part of the short-chain dehydrogenases/reductases (SDR) family which acts as a tumor suppressor in metabolic suppression, inhibition of angiogenesis and induces the expression of apoptosis related genes Bad and Siva. HTATIP2 cooperates with the activation domain of HIV-1 TAT and enhances its transcription by phosphorylating RNA polymerase II (Pol II). Defects in HTATIP2 are related with hepatocellular carcinomas and apoptotic resistant tumor cells, implicating a probable use for HTATIP2 in antitumor therapy.

NEDD8-activating enzyme E1 regulatory subunit (NAE1) is a member of the ubiquitin-activating E1 family. NAE1 binds to the beta-amyloid precursor protein. Beta-amyloid precursor protein is a cell surface protein with signal-transducing properties, and it is believed to have a role in the pathogenesis of Alzheimer's disease. NAE1 participates in a unique ubiquitinylation-related pathway involving the ubiquitin-like molecule NEDD8. Furthermore, the NAE1 protein is essential for cell cycle progression through the S/M checkpoint.

Scavenger mRNA-decapping enzyme (DCPS) is a member of the HIT family. DCPS is required for the complete degradation of mRNAs, both in normal mRNA turnover and in nonsense-mediated mRNA decay. It was shown that DCPS hydrolyzes the residual m7GpppN cap structure after the complete 3'–5' degradation of the mRNA by the exosome. Furthermore, DCPS releases m7GMP and is incapable of cleaving cap structures attached to a long RNA chain.

HEXA is the alpha subunit of the lysosomal enzyme beta-hexosaminidase which, combined with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules having N-acetyl hexosamines terminus. The two subunits composing Beta-hexosaminidase, alpha and beta, belong to the glycosyl hydrolases family and are encoded by distinct genes. Alpha subunit gene mutations can cause Tay-Sachs disease (GM2-gangliosidosis type I).

HEXA is the alpha subunit of the lysosomal enzyme beta-hexosaminidase which, combined with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules having N-acetyl hexosamines terminus. The two subunits composing Beta-hexosaminidase, alpha and beta, belong to the glycosyl hydrolases family and are encoded by distinct genes. Alpha subunit gene mutations can cause Tay-Sachs disease (GM2-gangliosidosis type I).

Chymotrypsinogen-B1 (CTRB1) belongs to the serine protease family of enzymes and forms a main precursor of the pancreatic proteolytic enzymes. CTRB1 is located next to a related chymotrypsinogen gene. CTRB1 is a protein coding gene which encodes different isoforms which may undergo similar processing to generate the mature protein.

HD Domain Containing 2, also known as HDDC2 is a member of the HDDC2 family. HDDC2 is an enzyme which contains one HD domain and it is expected to exhibit phosphohydrolase activity. It has been proposed that HDDC2 takes part in nucleic acid metabolism, signal transduction and possibly other functions in bacteria, archaea and eukaryotes. The HD domain consists of highly conserved residues, in particular histidines or aspartates. Porphyria cutanea tarda, Parkinson’s disease and Stickler syndrome have all been related with HDDC2.

Aspartoacylase 3 (ACY3) belongs to the Aspartoacylase subfamily. ACY3 has a vital role in deacetylating mercapturic acids in kidney proximal tubules. Aspartoacylase 3 localizes to the cytoplasm of S2 and S3 proximal tubules and also to the apical domain of S1 proximal tubules. In addition, ACY3 protein is expressed at low levels in the stomach, testis, heart, brain, lung and liver, and can function as an HCV (Hepatitis C virus) core binding protein.

ACO1 has a part in an iron sensor. ACO1 catalyzes the stereo-specific isomerization of citrate to isocitrate via cis-aconitate in the tricarboxylic acid cycle, a non-redox-active process.