• Purity

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

• Endotoxin Level

  <1.0 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by the ability of the immobilized protein to induce IFN-gamma secretion in NK‑92 human natural killer lymphoma cells. The ED    ₅₀ for this effect is typically 2-10 μg/mL.

• Source

  Mouse myeloma cell line, NS0-derived

  Human ULBP-4 (Gly30-Asp225) Accession # Q8TD07	IEGRMD	Human IgG1 (Pro100-Lys330)
  N-terminus		C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Gly30

• Structure / Form

  Disulfide-linked homodimer

• Predicted Molecular Mass

  49 kDa (monomer)

• SDS-PAGE

  60-65 kDa, reducing conditions

Background: ULBP-4/RAET1E

RAET1E (retinoic acid early transcript 1E), also called ULBP-4 (cytomegalovirus glycoprotein UL16 binding protein 4), Letal (lymphocyte effector cell toxicity activating ligand) and NKG2DL4 (NKG2D ligand 4), is a 40-50 kDa member of the RAET1/ULBP family of cell surface proteins that function as ligands for NKG2D (1‑6). While most family members are GPI-anchored, only RAET1E/ULBP-4 and ULBP-5/RAET1G express a transmembrane form (1, 4, 6, 7). Human RAET1E mRNA encodes 263 amino acids (aa) including a 30 aa signal sequence, a 195 aa extracellular domain (ECD), a 23 aa transmembrane domain, and a 15 aa cytoplasmic sequence. A soluble 35 kDa form diverges at aa 208 and is thought to antagonize the transmembrane form (5). Other potential splice variants of 220, 227 and 280 aa are transmembrane proteins (8). Within the ECD, RAET1E shares 34-41% aa sequence identity with family members (1, 7). Rodent NKG2D ligands Rae-1 alpha -epsilon are, like human ULBP and MIB proteins, distantly related to MHC class I proteins, but none of the families share significant sequence identity (2, 4). Low expression of RAET1E mRNA is found in normal tissues, with high expression variably reported in the small intestine (3) and skin (4). Expression is stimulated by TNF-alpha and down‑regulated by retinoic acid (3). RAET1E is abnormally expressed on most colon cancer and some other tumor cell lines and virus-infected peripheral blood cells (3, 6). RAET1E binds and costimulates NKG2D-expressing effector cells including NK cells, NKT cells, gamma δ T cells, and CD8  ⁺ alpha beta T cells, activating cytolytic activity and/or cytokine production (3, 4, 7). In some gamma δ T cells, direct RAET1E binding to both TCR gamma δ and NKG2D has been demonstrated (6). RAET1E is also thought to function as a minor histocompatibility antigen in humans (1).

• References:

1. Radosavljevic, M. et al. (2002) Genomics 79:114.

2. Kondo, M. et al. (2010) Immunogenetics 62:441.

3. Conejo-Garcia, J.R. et al. (2003) Cancer Biol. Ther. 2:446.

4. Chalupny, N.J. et al. (2003) Biochem. Biophys. Res. Commun. 305:129.

5. Cao, W. et al. (2007) J. Biol. Chem. 282:18922.

6. Kong, Y. et al. (2009) Blood 114:310.

7. Bacon, L. et al. (2004) J. Immunol. 173:1078.

8. Cao, W. et al. (2008) Int. Immunol. 20:981.

• Long Name:

  UL16 Binding Protein-4

• Entrez Gene IDs:

  135250 (Human); 379043 (Mouse); 292461 (Rat)

• Alternate Names:

  bA350J20.7; LETAL; LETALRAE-1-like transcript 4; Lymphocyte effector toxicity activation ligand; MGC125309; N2DL4; N2DL-4; NKG2D ligand 4; NKG2DL4; RAET1E; RAET1E2; retinoic acid early transcript 1ERL-4; RL-4; ULBP4; ULBP-4; ULBP4MGC125308