• Purity

  >95%, by SDS-PAGE under reducing conditions and visualized by silver stain

• Endotoxin Level

  <0.01 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its binding ability in a functional ELISA. Immobilized Recombinant Human PRAT4A at 2 μg/mL can bind Recombinant Human TLR4/MD‑2 Complex (Catalog # ) with an apparent K    _D <15 nM.  

• Source

  Mouse myeloma cell line, NS0-derived Glu38-Leu278, with a C-terminal 6-His tag

• Accession #

• N-terminal Sequence    
  Analysis

  Glu38

• Predicted Molecular Mass

  26.9 kDa

• SDS-PAGE

  37-40 kDa, reducing conditions

Background: PRAT4A

PRAT4A (PRotein Associated with Toll-like receptor 4A), also called CNPY3 (Canopy homolog 3) or TNRC5 (trinucleotide repeat-containing 5) is a widely expressed 40 kDa protein that is an intracellular chaperone for Toll-like receptors (TLRs) (1-3). Human PRAT4A cDNA encodes 278 amino acids (aa), including an N-terminal hydrophobic sequence of 26-37 aa (putative signal sequence) and a 250-241 aa mature region (3). A potential 153 aa form has an alternate start site at aa 126. Human PRAT4A shares 90%, 90%, 94%, 95% and 96% aa sequence identity with mouse, rat, bovine, canine and porcine PRAT4A, respectively. A related protein, PRAT4B, shares approximately 40% aa sequence identity, is co‑expressed, and is reported to bind TLR4 only if it lacks mature glycosylated structures (4). PRAT4A resides in the endoplasmic reticulum (ER) and is a co‑chaperone that provides substrate-specificity to the chaperone gp96, an HSP90 paralog required for proper folding of TLRs (1‑3, 5, 6). It binds TLR4, enhances TLR4 N-linked glycosylation, and forms a heterotrimer with TLR4 and its co‑receptor, MD2 (6-8). PRAT4A is required for transfer of TLR4 from the ER to the plasma membrane where it recognizes its extracellular ligand, bacterial lipopolysaccharide (LPS) (1‑3, 6, 7). PRAT4A is also essential for maturation and trafficking of TLR9 from the ER to endolysosomes in response to its intracellular ligand, unmethylated DNA (1‑3, 5‑7, 9). PRAT4A deletion, knockdown, or specific mutation in mice abolishes or lowers surface expression of TLR4/MD2, TLR2, TLR1 and RP105/CD180, and abolishes production of RANTES in response to a TLR7 ligand (3, 6-8). PRAT4A enhances Th1 responses and production of inflammatory cytokines in response to TLR ligands, and thus contributes to endotoxic shock (2, 6‑8).

• References:

1. McGettrick, A.F. and L.A.J. O’Neill (2010) Curr. Opin. Immunol. 22:20.

2. Akashi-Takamura, S. and K. Miyake (2008) Curr. Opin. Immunol. 20:420.

3. Wakabayashi, Y. et al. (2006) J. Immunol. 177:1772.

4. Konno, K. et al. (2006) Biochem. Biophys. Res. Commun. 339:1076.

5. Liu, B. et al. (2010) Nat. Commun. 1:79.

6. Takahashi, K. et al. (2007) J. Exp. Med. 204:2963.

7. Kiyokawa, T. et al. (2008) Int. Immunol. 20:1407.

8. Shibata, T. et al. (2011) Int. Immunol. 23:503.

9. Saitoh, S-I. and K. Miyake (2009) Immunol. Rev. 227:32.

• Long Name:

  Protein Associated with Toll-like Receptor 4A

• Entrez Gene IDs:

  10695 (Human); 72029 (Mouse); 316225 (Rat)

• Alternate Names:

  CAG4A; canopy 3 homolog (zebrafish); CNPY3; CTG4A; ERDA5; ERDA5CTG repeat protein 4a; Expanded repeat-domain protein CAG/CTG 5; PRAT4A; PRAT4ACAG repeat containing; Protein associated with TLR4; protein associated with Toll-like receptor 4A; protein canopy homolog 3; TNRC5; TNRC5expanded repeat domain, CAG/CTG 5; trinucleotide repeat containing 5; Trinucleotide repeat-containing gene 5 protein