ap site

Human N-Glycosylase/DNA Lyase(OOG1) is a DNA repair enzyme, which belongs to the type-1 OGG1 family. OOG1 incises DNA at 8-oxoG residues, and excises 7,8-dihydro-8-oxoguanine and 2,6-diamino-4-hydroxy-5-N-methylformamidopyrimidine (FAPY) from damage DNA. It has a β-lyase activity that nicks DNA 3’ to the lesion. OOG1 together with APEX1 is recruited to nuclear speckles in UVA-irradiated cells. The OGG1 gene mutations may be caused Renal cell carcinoma.

Apurinic-Apyrimidinic Endonuclease 1 (APE1) is required for efficient DNA base excision repair. When the DNA glycosylase remove the damaged bases, APE1 cleaves the AP site to allow resynthesis and ligation to complete repair. APE1 stimulates the DNA binding activity of many transcription factors, which participate in cancer promotion and progression. APE1 regulates the redox state of multiple transcription factors, such as c-Jun, c-Fos, NF-kB, p53. APEN is also involved in calcium-dependent down-regulation of PTH expression.

UBCH8, also known as UBE2L6, belongs to the ubiquitin-conjugating enzyme family. The family of ubiquitin-conjugating (E2) enzymes is characterized by the presence of a highly conserved ubiquitin-conjugating (UBC) domain. These domains accommodate the ATP-activated ubiquitin (Ub) or ubiquitin-like (UBL) protein via a covalently linked thioester onto its active-site residue. E2 enzymes act via selective protein-protein interactions with the E1 and E3 enzymes and connect activation to covalent modification. By doing so, E2s differentiate effects on downstream substrates, either with a single Ub/UBL molecule or as a chain. UBCH8 is highly similar in primary structure to the enzyme encoded by the UBE2L3 gene. It catalyzes the covalent attachment of ubiquitin or ISG15 to other proteins. UBCH8 functions in the E6/E6-AP-induced ubiquitination of p53/TP53 and promotes ubiquitination and subsequent proteasomal degradation of FLT3. At protein level, it is present in natural killer cells.

Mothers against decapentaplegic homolog 3(SMAD3) is a cytoplasm protein which belongs to the dwarfin/SMAD family. Smad proteins undergo rapid nuclear translocation upon stimulation by transforming growth factor and in so doing transduce the signal into the nucleus. Receptor-regulated SMAD is an intracellular signal transducer and transcriptional modulator activated by TGF-beta and activin type 1 receptor kinases. SMAD3 binds the TRE element in the promoter region of many genes that are regulated by TGF-beta and, on formation of the SMAD3/SMAD4 complex, activates transcription. It also can form a SMAD3/SMAD4/JUN/FOS complex at the AP-1/SMAD site to regulate TGF-beta-mediated transcription. SMAD3 has an inhibitory effect on wound healing probably by modulating both growth and migration of primary keratinocytes and by altering the TGF-mediated chemotaxis of monocytes. This effect on wound healing appears to be hormone-sensitive.

NEIL1 is a member of DNA glycosylases. DNA glycosylases are a family homologous to the bacterial Fpg/Nei family. They play a role in base excision repair which is the mechanism by which damaged bases in DNA are removed and replaced. The first step of this process is catalyzed by DNA glycosylases. They remove the damaged nitrogenous base while leaving the sugar-phosphate backbone intact, creating an apurinic/apyrimidinic site, commonly referred to as an AP site. NEIL1 functions in base excision repair of DNA damaged by oxidation or by mutagenic agents. It acts as a DNA glycosylase that recognizes and removes damaged bases. NEIL1 prefers to oxidized pyrimidines, such as thymine glycol, Formamidopyrimidine (Fapy), and 5-hydroxyuracil. Has marginal activity towards 8-oxoguanine. It has AP (apurinic/apyrimidinic) lyase activity and introduces nicks in the DNA strand and cleaves the DNA backbone by beta-delta elimination to generate a single-strand break at the site of the removed base with both 3'- and 5'-phosphates.