• Purity

  >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.

• Endotoxin Level

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

• Activity

  Measured by its ability to bind human IgG with an estimated K    _D <30 nM.  

• Source

  Mouse myeloma cell line, NS0-derived Gln16-Arg844 with a C-terminal 6-His tag

• Accession #

• N-terminal Sequence    
  Analysis

  No results obtained: Gln16 predicted

• Predicted Molecular Mass

  91.5 kDa

• SDS-PAGE

  110-120 kDa, reducing conditions

Background: FCRL5/FcRH5

Fc Receptor-Like 5 (FCRL5), also known as FcRH5, IRTA2, and CD307, is a 120 kDa protein with sequence homology to classical Fc receptors. The type 1 transmembrane FCRL proteins contain from three to nine immunoglobulin-like domains. They are differentially expressed within the B cell lineage and can either promote or inhibit B cell proliferation and activation (1, 2). According to R&D Systems testing, FCRL5 binds to purified human IgG with high affinity. Mature human FCRL5 consists of a 836 amino acid (aa) extracellular domain (ECD) with nine Ig-like domains, a 21 aa transmembrane segment, and a 105 aa cytoplasmic domain with one immunotyrosine activation motif (ITAM) and two immunotyrosine inhibitory motifs (ITIMs) (1, 3). Mouse FCRL5 contains only five Ig-like domains in its ECD. It shares 49% aa sequence identity with human FCRL5 within common regions. Alternate splicing of human FCRL5 generates isoforms that consist of approximately the first one, six, or eight Ig-like domains (3, 4). FCRL5 expression is restricted to mature B lineage cells in lymphoid tissues and blood (3, 5 - 7). Its ligation inhibits signaling through the B cell antigen receptor (8). Epstein-Barr virus transformation of B cells induces the upregulation of surface FCRL5 by a direct effect of its EBNA2 protein on FCRL5 gene transcription (9). The FCRL5 gene maps to the 1q21 chromosomal locus, a common site of rearrangements in B cell malignancies, and the FCRL5 protein is preferentially expressed in cell lines with 1q21 abnormalities (3). FCRL5 is upregulated on tumor cells in some types of B cell malignancies (6, 10 - 12). In addition, soluble FCRL5 is elevated in the serum of many B cell leukemia patients (11, 13).

• References:

1. Davis, R.S. (2007) Annu. Rev. Immunol. 25:525.

2. Maltais, L.J. et al. (2006) Nat. Immunol. 7:431.

3. Hatzivassiliou, G. et al. (2001) Immunity 14:277.

4. SwissProt # Q96RD9

5. Miller, I. et al. (2002) Blood 99:2662.

6. Polson, A.G. et al. (2006) Int. Immunol. 18:1363.

7. Vidal-Laliena, M. et al. (2005) Cell. Immunol. 236:6.

8. Haga, C.L. et al. (2007) Proc. Natl. Acad. Sci. 104:9770.

9. Mohan, J. et al. (2006) Blood 107:4433.

10. Ise, T. et al. (2005) Clin. Cancer Res. 11:87.

11. Ise, T. et al. (2007) Leukemia 21:169.

12. Kazemi, T. et al. (2009) Cancer Immunol. Immunother. 58:989.

13. Ise, T. et al. (2006) Clin. Chem. Lab. Med. 44:594.

• Long Name:

  Fc Receptor-like 5

• Entrez Gene IDs:

  83416 (Human); 329693 (Mouse)

• Alternate Names:

  BXMAS1; BXMAS1MGC119592; CD307; CD307e antigen; CD307e; DKFZp667E2019; DKFZp667F216; Fc receptor homolog 5; Fc receptor-like 5; Fc receptor-like protein 5; FcRH5; FCRH5MGC119593; FCRL5; FcR-like protein 5; FLJ00333; FLJ00397; IFGP5; Immune receptor translocation-associated protein 2; immunoglobulin superfamily receptor translocation associated 2 (IRTA2); IRTA2; IRTA2MGC119590; PRO820