Recombinant Human ULBP-4/RAET1E Fc Chimera Protein, CF

Recombinant Human ULBP-4/RAET1E Fc Chimera Protein, CF Summary

Product Specifications

Product Datasheets

Carrier Free

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.

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).

Related Research Areas

• NKG2D Receptors and Ligands