• 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 its binding ability in a functional ELISA. When Recombinant Human (rh) NKG2D Fc Chimera (Catalog # ) is immobilized at 1 μg/mL (100 μL/well), the concentration of rhULBP-5 that produces 50% of the optimal binding response is found to be approximately 1.5-7.5 ng/mL.

• Source

  Chinese Hamster Ovary cell line, CHO-derived Met1-Gly210, with a C-terminal 6-His tag

• Accession #

• N-terminal Sequence    
  Analysis

  Asp29

• Predicted Molecular Mass

  21.5 kDa

• SDS-PAGE

  24-28 kDa, reducing conditions

Background: ULBP-5

ULBP?5 (cytomegalovirus glycoprotein UL16 binding protein 5), also called RAET1G (retinoic acid early transcript 1G), is a 37 kDa member of a family of cell?surface proteins that function as ligands for human NKG2D (1?3). When engaged, NKG2D activates cytolytic activity and/or cytokine production by effector cells that express it, such as NK cells, NKT cells, gamma δ T cells, and CD8⁺ alpha beta  T cells (3?5). Human ULBP?5 mRNA encodes a 25 amino acid (aa) signal sequence, a 198 aa extracellular domain (ECD), a 20 aa transmembrane domain, and a 91 aa cytoplasmic sequence. Transmembrane, predicted soluble (RAET1G2), and glycosylphosphatidylinositol (GPI)?anchored isoforms are identical through aa 210, while a shorter soluble form (RAET1G3) lacks aa 118?154 (3?5). Secreted, cell surface and intracellular ULBP?5 have been described (3?8). While most family members are GPI?anchored, only ULBP?5 and ULBP?4/RAET1E express a transmembrane form (4, 5). Within the ECD, ULBP?5 possesses two MHC Class I alpha domains and shares ~93% aa sequence identity with ULBP?2/RAET1H plus ULBP?6/RAET1L, and 30?60% aa identity with remaining family members (1, 5). Rodent NKG2D ligands Rae?1  alpha ? epsilon are, like ULBP proteins, distantly related to MHC class I proteins, but ULBP and Rae?1 family proteins do not share significant sequence identity (2). ULBP?5 mRNA expression is low or undetected in many tissues, but increased expression is reported in epithelial tissues and human decidua (5?8). ULBP?5 is expressed on some breast, epithelial and hematopoietic tumor cells and has been implicated in tumor surveillance (4?6).

• References:

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

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

3. Ohashi, M. et al. (2010) J. Biol. Chem. 285:16408.

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

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

6. Eagle, R.A. et al. (2009) PLoS ONE 4:e4503.

7. Wittenbrink, M. et al. (2009) Eur. J. Immunol. 39:1642.

8. Apps, R. et al. (2008) Hum. Reprod. 23:2535.

• Long Name:

  UL16 Binding Protein-5

• Entrez Gene IDs:

  353091 (Human)

• Alternate Names:

  RAET1G; retinoic acid early transcript 1G protein; retinoic acid early transcript 1G pseudogene; retinoic acid early transcript 1G; ULBP5; ULBP-5