cGAS Protein, Human (His)

cGAS is a cytosolic DNA sensor. cGAS binds double-stranded DNA (dsDNA) and catalyzes the generation of cyclic guanosine-adenylate (cGAMP), which in turn activates the STING protein. cGAS induces the production of type I interferon (IFN-I) and pro-inflammatory cytokines. cGAS Protein, Human (His) is a recombinant cGAS protein expressed in E. coli with a C-6*His tag.

cGAS belongs to the nucleotidyltransferase family^[1]. cGAS is a cytoplasmic DNA sensor that can bind to double-stranded DNA (dsDNA) and catalyze the generation of cyclic guanosine-adenylate (cGAMP), which in turn activates the STING protein and initiates the type I interferon (IFN-I) pathway^[1][2]. After cGAS binds to cytoplasmic DNA, it undergoes a conformational change and catalyzes ATP and GTP to generate cGAMP with a 2′-5′/3′-5′ phosphodiester bond. cGAMP binds to and activates STING, ultimately inducing IRF3 dimerization and the expression of IFN-I and proinflammatory cytokines^[2][6]. cGAS is expressed in a variety of cells, including monocyte-derived dendritic cells (moDC), macrophages (MF), plasmacytoid dendritic cells (pDC), HEK293T cells, THP1 cells, etc., and its expression level in immune cells can be upregulated by viral infection or IFN-α induction^[5][6]. cGAS, Human and cGAS homologs from other species such as mice have sequence and structural homology in the catalytic domain, but there are species-specific differences. For example, the catalytic efficiency of human cGAS is lower than that of mice, and differences in some regulatory sites (such as K187 and L195) affect its binding to DNA and activation mode^[1][4]. cGAS, Human consists of an N-terminal disordered region (1-156 amino acids) and a C-terminal structured catalytic domain (157-522 amino acids). The catalytic domain contains a nucleotidyltransferase (NTase) domain and a Mab21 domain, which is the functional core that binds DNA and catalyzes the synthesis of cGAMP^[4]. The activity of cGAS, Human depends on DNA binding, and its efficiency in catalyzing the production of cGAMP is affected by DNA length, conformation, and histone binding status. For example, nucleosome binding reduces its activity. In addition, its activity can be specifically inhibited by small molecule inhibitors (such as RU.521)^[3][5].

cGAS Protein, Human can be activated by HCMV DNA to synthesize cGAMP^[6].

Enzyme activity has been tested in vitro.

Human

E. coli

C-6*His

Q8N884-1 (M1-F522)

115004  [NCBI]

Full Length of Isoform-1

MQPWHGKAMQRASEAGATAPKASARNARGAPMDPTESPAAPEAALPKAGKFGPARKSGSRQKKSAPDTQERPPVRATGARAKKAPQRAQDTQPSDATSAPGAEGLEPPAAREPALSRAGSCRQRGARCSTKPRPPPGPWDVPSPGLPVSAPILVRRDAAPGASKLRAVLEKLKLSRDDISTAAGMVKGVVDHLLLRLKCDSAFRGVGLLNTGSYYEHVKISAPNEFDVMFKLEVPRIQLEEYSNTRAYYFVKFKRNPKENPLSQFLEGEILSASKMLSKFRKIIKEEINDIKDTDVIMKRKRGGSPAVTLLISEKISVDITLALESKSSWPASTQEGLRIQNWLSAKVRKQLRLKPFYLVPKHAKEGNGFQEETWRLSFSHIEKEILNNHGKSKTCCENKEEKCCRKDCLKLMKYLLEQLKERFKDKKHLDKFSSYHVKTAFFHVCTQNPQDSQWDRKDLGLCFDNCVTYFLQCLRTEKLENYFIPEFNLFSSNLIDKRSKEFLTKQIEYERNNEFPVFDEF

Approximately 58.9 kDa

• 
  Greater than 95% as determined by reducing SDS-PAGE.

Solution

Supplied as a 0.2 μm filtered solution of 20 mM Tris HCl, 100 mM NaCl, 1 mM DTT, 5% Glycerol, pH 7.5.

<1 EU/μg, determined by LAL method.

Stored at -80°C for 1 year from date of receipt. It is stable at -20°C for 3 months after opening. It is recommended to freeze aliquots at -80°C for extended storage. Avoid repeated freeze-thaw cycles.

Shipping with dry ice.

• [1]. Sun L, et al. Cyclic GMP-AMP synthase is a cytosolic DNA sensor that activates the type I interferon pathway. Science. 2013 Feb 15;339(6121):786-91.  [Content Brief]

  [2]. Ablasser A, et al. cGAS produces a 2'-5'-linked cyclic dinucleotide second messenger that activates STING. Nature. 2013 Jun 20;498(7454):380-4.  [Content Brief]

  [3]. Wiser C, et al. Small molecule inhibition of human cGAS reduces total cGAMP output and cytokine expression in cells. Sci Rep. 2020 May 5;10(1):7604.  [Content Brief]

  [4]. Zhou W, et al. Analysis of human cGAS activity and structure. Methods Enzymol. 2019;625:13-40. doi: 10.1016/bs.mie.2019.04.012. Epub 2019 May 2.  [Content Brief]

  [5]. Wang H, et al. Cellular uptake of extracellular nucleosomes induces innate immune responses by binding and activating cGMP-AMP synthase (cGAS). Sci Rep. 2020 Sep 21;10(1):15385.  [Content Brief]

  [6]. Paijo J, et al. cGAS Senses Human Cytomegalovirus and Induces Type I Interferon Responses in Human Monocyte-Derived Cells. PLoS Pathog. 2016 Apr 8;12(4):e1005546.  [Content Brief]