non-catalytic

The enzyme oligosaccharyltransferase (dolichyl-diphosphooligosaccharide-protein glycosyltransferase) (DDOST), or 48-kDa subunit (OST48) is one of the catalytic subunits in this complex, exerts a typical type I membrane topology, containing a large luminal domain, a hydrophobic transmembrane domain and a short cytosolic peptide tail. DDOST OST48 catalyzes the transfer of a high-mannose oligosaccharide (GlcNac2Man9Glc3) from a dolichol-linked oligosaccharide donor (dolichol-P-GlcNac2Man9Glc3) onto the asparagine acceptor site within an Asn-X-Ser Thr consensus motif in nascent polypeptide chains across the membrane of the endoplasmic reticulum. The mammalian oligosaccharyltransferase (OST) is an oligomeric complex composed of three type I transmembrane proteins of the endoplasmic reticulum: ribophorin I (RI), ribophorin II (RII), and OST48. OST48 is not a glycoprotein and is not recognized by antibodies to either ribophorin. Like ribophorins I and II, OST48 was found to be an integral membrane protein, with the majority of the polypeptide located within the lumen of the endoplasmic reticulum (ER). OST48 does not show significant amino acid sequence homology to either ribophorin I or II. It had been found that only the luminal domain of RI contains ER retention information. The dilysine motif in OST48 functions as an ER localization motif because OST48 in which the two lysine residues are replaced by serine (OST48ss) is no longer retained in the ER and is found instead also at the plasma membrane.

Mouse Metalloproteinase inhibitor 2(TIMP-2), belongs to a family of proteins that regulate the activation and proteolytic activity of matrix metalloproteinases (MMPs). There are four mammalian members of the family; TIMP‑1, TIMP‑2, TIMP‑3, and TIMP‑4. The TIMP-2 is detected in testis, retina, hippocampus and cerebral cortex. The function of TIMP 2 protein is to inhibit MMPs non covalently by the formation of binary complexes. Complexes with metalloproteinases (such as collagenases) and irreversibly inactivates them by binding to their catalytic zinc cofactor.And the interaction with MMP-14 facilitates the activation of pro-MMP-2.It has been shown that the binding of TIMP 2 to a3b1 integrin results in the inhibition of endothelial cell proliferation and angiogenesis.

Single-stranded DNA-dependent ATP-dependent helicase that plays a key role in DNA non-homologous end joining (NHEJ) by recruiting DNA-PK to DNA. Required for double-strand break repair and V(D)J recombination. Also has a role in chromosome translocation. The DNA helicase II complex binds preferentially to fork-like ends of double-stranded DNA in a cell cycle-dependent manner. It works in the 3'-5' direction. During NHEJ, the XRCC5-XRRC6 dimer performs the recognition step: it recognizes and binds to the broken ends of the DNA and protects them from further resection. Binding to DNA may be mediated by XRCC6. The XRCC5-XRRC6 dimer acts as regulatory subunit of the DNA-dependent protein kinase complex DNA-PK by increasing the affinity of the catalytic subunit PRKDC to DNA by 100-fold. The XRCC5-XRRC6 dimer is probably involved in stabilizing broken DNA ends and bringing them together. The assembly of the DNA-PK complex to DNA ends is required for the NHEJ ligation step. The XRCC5-XRRC6 dimer probably also acts as a 5'-deoxyribose-5-phosphate lyase (5'-dRP lyase), by catalyzing the beta-elimination of the 5' deoxyribose-5-phosphate at an abasic site near double-strand breaks. XRCC5 probably acts as the catalytic subunit of 5'-dRP activity, and allows to 'clean' the termini of abasic sites, a class of nucleotide damage commonly associated with strand breaks, before such broken ends can be joined. The XRCC5-XRRC6 dimer together with APEX1 acts as a negative regulator of transcription. In association with NAA15, the XRCC5-XRRC6 dimer binds to the osteocalcin promoter and activates osteocalcin expression. As part of the DNA-PK complex, involved in the early steps of ribosome assembly by promoting the processing of precursor rRNA into mature 18S rRNA in the small-subunit processome. Binding to U3 small nucleolar RNA, recruits PRKDC and XRCC5 Ku86 to the small-subunit processome. Plays a role in the regulation of DNA virus-mediated innate immune response by assembling into the HDP-RNP complex, a complex that serves as a platform for IRF3 phosphorylation and subsequent innate immune response activation through the cGAS-STING pathway.

HCV NS3 displays three enzymatic activities: serine protease, NTPase, and RNA helicase. HCV NS3 serine protease, in association with NS4A, is responsible for the cleavages of NS3-NS4A, NS4A-NS4B, NS4B-NS5A, and NS5A-NS5B. HCV NS3 RNA helicase binds to RNA and unwinds dsRNA in the 3' to 5' direction, and likely RNA stable secondary structure in the template strand (By similarity). Cleaves and inhibits the host antiviral protein MAVS. NS3 NS4A complex also prevents phosphorylation of human IRF3, thus preventing the establishment of dsRNA induced antiviral state. One of the HCV proteases, NS3-4A serine protease, is a non-covalent heterodimer consisting of a catalytic subunit (the N-terminal one-third of NS3 protein) and an activating cofactor (NS4A protein) and is responsible for cleavage at four sites of the HCV polyprotein.

ATP1B1 belongs to the family of Na+ K+and H+ K+-ATPases beta chain proteins, and to the subfamily of Na+ K+ -ATPases. ATP1B1 is a subunit of Na+ K+-ATPase. Na+ K+-ATPase is an integral membrane protein responsible for establishing and maintaining the electrochemical gradients of Na and K ions across the plasma membrane. Na+ K+-ATPase is composed of two subunits, a large catalytic subunit (alpha) and a smaller glycoprotein subunit (beta). ATP1B1 regulates, through assembly of alpha beta heterodimers, the number of sodium pumps transported to the plasma membrane. ATP1B1 is the non-catalytic component of the active enzyme, which catalyzes the hydrolysis of ATP coupled with which catalyzes the hydrolysis of ATP coupled with the exchange of Na+and K+ions across the plasma membrane.

Plays a key role in the repair of DNA damage, functioning as part of both the non-homologous end-joining (NHEJ) and base excision repair (BER) pathways. Through its two catalytic activities, PNK ensures that DNA termini are compatible with extension and ligation by either removing 3'-phosphates from, or by phosphorylating 5'-hydroxyl groups on, the ribose sugar of the DNA backbone. PNKP Protein, Human, Recombinant (His & SUMO) is expressed in E. coli expression system with N-6xHis-SUMO tag. The predicted molecular weight is 73.1 kDa and the accession number is Q96T60.

PAH (phenylalanine hydroxylase), also known as PH, belongs to the biopterin-dependent aromatic amino acid hydroxylase family. It contains 1 ACT domain, N-terminal region of PAH is thought to contain allosteric binding sites for phenylalanine and to constitute an inhibitory domain that regulates the activity of a catalytic domain in the C-terminal portion of the molecule. In humans, PAH is expressed both in the liver and the kidney, and there is some indication that it may be differentially regulated in these tissues. PAH catalyzes the hydroxylation of the aromatic side-chain of phenylalanine to generate tyrosine. It is one of three members of the pterin-dependent amino acid hydroxylases, a class of monooxygenase that uses tetrahydrobiopterin and a non-heme iron for catalysis. Defects in PAH are the cause of phenylketonuria (PKU). PKU is an autosomal recessive inborn error of phenylalanine metabolism, due to severe phenylalanine hydroxylase deficiency. It is characterized by blood concentrations of phenylalanine persistently above 1200 mumol.

Mannoside Acetylglucosaminyltransferase 2 (MGAT2) is a single-pass type II membrane protein that contains the typical glycosyltransferase domains: a short N-terminal cytoplasmic domain, a hydrophobic non-cleavable signal-anchor domain and a C-terminal catalytic domain. MGAT2 catalyzes an essential step in the conversion of oligo-mannose to complex N-glycans. Defects in MGAT2 are the cause of congenital disorder of glycosylation type 2A.

Aldehyde dehydrogenase 3A1 (ALDH3A1) is a metabolic enzyme that catalyzes the oxidation of various aldehydes. Certain types of epithelial tissues in mammals, especially those continually exposed to environmental stress (e.g., corneal epithelium), express ALDH3A1 at high levels and its abundance in such tissues is perceived to help to maintain cellular homeostasis under conditions of oxidative stress. Metabolic as well as non-metabolic roles for ALDH3A1 have been associated with its mediated resistance to cellular oxidative stress. Aldehyde dehydrogenase 1A1 (ALDH1A1) and ALDH3A1 are corneal crystallins. They protect inner ocular tissues from ultraviolet radiation (UVR)-induced oxidative damage through catalytic and non-catalytic mechanisms. Additionally, ALDH3A1 has been postulated to play a regulatory role in the corneal epithelium based on several studies that report an inverse association between ALDH3A1 expression and corneal cell proliferation. Aldehyde dehydrogenase 3A1 (ALDH3A1) plays an important role in many cellular oxidative processes, including cancer chemoresistance, by metabolizing activated forms of oxazaphosphorine drugs such as cyclophosphamide (CP) and its analogues, such as mafosfamide (MF), ifosfamide (IFM), and 4-hydroperoxycyclophosphamide (4-HPCP). Compounds that can selectively target ALDH3A1 could permit delineation of its roles in these processes and could restore chemosensitivity in cancer cells that express this isoenzyme. ALDH3A1 may act to protect corneal cells against cellular oxidative damage by metabolizing toxic lipid peroxidation products (e.g., 4-HNE), maintaining cellular GSH levels and redox balance, and operating as an antioxidant.

Ubiquitin-Conjugating Enzyme Variant 1a (UBE2V1) is a member of the Ubiquitin-conjugating (E2) enzyme family. The E2 catalytic core domain of UBE2V1 lacks an active site cysteine residue, rendering it catalytically inactive on its own. However, in the cytoplasm UBE2V1 is able to form a catalytically active complex with UBE2N Ubc13, which mediates the synthesis Lys63-linked Ubiquitin chains and is required for NF-kappa B activation. UBE2V1 is required for UBE2N (Ubc13) UBE2V1 Complex-dependent Lys63-linked Ubiquitin chain formation. More specifically, UBE2V1 orients the Ubiquitin molecule to favor linkage at Lys63 via a non-covalent interaction with the Ubiquitin molecule. The UBE2V1-UBE2N heterodimer catalyzes the synthesis of non-canonical poly-ubiquitin chains that are linked through Lys63. This type of poly-ubiquitination activates IKK and does not seem to involve protein degradation by the proteasome. UBE2V1 plays a role in the activation of NF-kappa-B mediated by IL1B, TNF, TRAF6, and TRAF2. It mediates transcriptional activation of target genes. UBE2V1 also controls the progress through the cell cycle and differentiation, the error-free DNA repair pathway and contributes to the survival of cells after DNA damage.

Single-stranded DNA-dependent ATP-dependent helicase that plays a key role in DNA non-homologous end joining (NHEJ) by recruiting DNA-PK to DNA. Required for double-strand break repair and V(D)J recombination. Also has a role in chromosome translocation. The DNA helicase II complex binds preferentially to fork-like ends of double-stranded DNA in a cell cycle-dependent manner. It works in the 3'-5' direction. During NHEJ, the XRCC5-XRRC6 dimer performs the recognition step: it recognizes and binds to the broken ends of the DNA and protects them from further resection. Binding to DNA may be mediated by XRCC6. The XRCC5-XRRC6 dimer acts as regulatory subunit of the DNA-dependent protein kinase complex DNA-PK by increasing the affinity of the catalytic subunit PRKDC to DNA by 100-fold. The XRCC5-XRRC6 dimer is probably involved in stabilizing broken DNA ends and bringing them together. The assembly of the DNA-PK complex to DNA ends is required for the NHEJ ligation step. The XRCC5-XRRC6 dimer probably also acts as a 5'-deoxyribose-5-phosphate lyase (5'-dRP lyase), by catalyzing the beta-elimination of the 5' deoxyribose-5-phosphate at an abasic site near double-strand breaks. XRCC5 probably acts as the catalytic subunit of 5'-dRP activity, and allows to 'clean' the termini of abasic sites, a class of nucleotide damage commonly associated with strand breaks, before such broken ends can be joined. The XRCC5-XRRC6 dimer together with APEX1 acts as a negative regulator of transcription. In association with NAA15, the XRCC5-XRRC6 dimer binds to the osteocalcin promoter and activates osteocalcin expression. As part of the DNA-PK complex, involved in the early steps of ribosome assembly by promoting the processing of precursor rRNA into mature 18S rRNA in the small-subunit processome. Binding to U3 small nucleolar RNA, recruits PRKDC and XRCC5 Ku86 to the small-subunit processome. Plays a role in the regulation of DNA virus-mediated innate immune response by assembling into the HDP-RNP complex, a complex that serves as a platform for IRF3 phosphorylation and subsequent innate immune response activation through the cGAS-STING pathway.

Tissue inhibitors of metalloproteinases or TIMPs are a family of proteins that regulate the activation and proteolytic activity of the zinc enzymes known as matrix metalloproteinases (MMPs). There are four members of the family, TIMP-1, TIMP-2, TIMP-3, and TIMP-4. Tissue Inhibitor of Metalloproteinases 2 (TIMP-2) is a non N-glycosylated protein with a molecular mass of 22 kDa. It produced by a wide range of cell types, which inhibits MMPs non-covalently by the formation of binary complexes and irreversibly inactivates them by binding to their catalytic zinc cofactor. TIMP-2 also has erythroid‑potentiating and cell growth promoting activities.

DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. Largest and catalytic core component of RNA polymerase III which synthesizes small RNAs, such as 5S rRNA and tRNAs. Forms the polymerase active center together with the second largest subunit. A single-stranded DNA template strand of the promoter is positioned within the central active site cleft of Pol III. A bridging helix emanates from RPC1 and crosses the cleft near the catalytic site and is thought to promote translocation of Pol III by acting as a ratchet that moves the RNA-DNA hybrid through the active site by switching from straight to bent conformations at each step of nucleotide addition. Plays a key role in sensing and limiting infection by intracellular bacteria and DNA viruses. Acts as nuclear and cytosolic DNA sensor involved in innate immune response. Can sense non-self dsDNA that serves as template for transcription into dsRNA. The non-self RNA polymerase III transcripts, such as Epstein-Barr virus-encoded RNAs (EBERs) induce type I interferon and NF- Kappa-B through the RIG-I pathway.