Detection of FCRL5 in Mouse Splenocytes by Flow Cytometry. Mouse splenocytes were stained with Rat Anti-Mouse B220/CD45R APC‑conjugated Monoclonal Antibody (Catalog # FAB1217A) and either (A) Sheep Anti-Mouse FCRL5 PE‑conjugated Antigen Affinity-purified Polyclonal Antibody (Catalog # FAB6757P) or (B) Normal Sheep IgG Phycoerythrin Control (Catalog # IC016P). View our protocol for Staining Membrane-associated Proteins.
Preparation and Storage
The product is shipped with polar packs. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage
Protect from light. Do not freeze.
12 months from date of receipt, 2 to 8 °C as supplied.
Fc Receptor-Like 5 (FCRL5), also known as FcRH3 (FcRH5 in human), mBXMH2, and CD307e, is a 90‑95 kDa member of the FCRL family of proteins whose amino acid (aa) sequence is reminiscent of that for classical Fc receptors. FCLR molecules are type 1 transmembrane proteins that 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, 3). Mature mouse FCRL5 consists of a 470 aa extracellular domain (ECD), a 21 aa transmembrane segment, and a 79 aa cytoplasmic region. The ECD contains five Ig-like domains, while the cytoplasmic region possesses one ITAM-like motif and one immunotyrosine inhibitory motif (ITIM) (1, 3, 4). There are two major alleles for FCLR5 in mouse. The first was just described, and is found in BALB/c plus NZB mouse strains. The second is found in C57BL/6 mice, and differs by eleven scattered aa in the ECD. This creates one additional N-linked glycosylation site, and increases the SDS‑PAGE MW by 5 kDa (3). Alternate splicing of mouse FCRL5 generates at least one additional isoform that lacks the first Ig-like domain (aa 3‑90 of the mature molecule) (4). Human FCRL5, by contrast, contains up to nine Ig-like domains in a highly variable ECD, and over common regions, mouse and human FCRL5 share 49% aa sequence identity. FCRL5 expression is restricted to mature B lineage cells in lymphoid tissues and blood, and is particularly prominent on T‑independent marginal zone and B1 B cells (3-8). Its ligation inhibits signaling through the B cell antigen receptor (9). Epstein-Barr virus transformation of B cells induces the up‑regulation of surface FCRL5 by a direct effect of its EBNA2 protein on FCRL5 gene transcription (10). FCRL5 on B cells functions as a receptor for the orthopoxvirus MHC class I-like protein OMCP (11). And based on the literature and R&D Systems testing, both mouse and human FCRL5 will bind to purified IgG with high affinity (5). In human, the FCRL5 gene maps to the 1q21 chromosomal locus, a common site of rearrangements in B cell malignancies and soluble FCRL5 is elevated in the serum of many B cell leukemia patients (12).
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Fc Receptor-like 5
Entrez Gene IDs:
83416 (Human); 329693 (Mouse)
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
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