| LMIR3, also known as CD300LF, CD300F, IREM-1, CLM-1, IgSF13, DIgR1, and MAIR-V, is a 50-60kD glycoprotein member of the immunoglobulin superfamily. Human LMIR3 consists of a 137aa extracellular domain (ECD) with one Ig-like V-type domain, a 21aa transmembrane segment, and a 113aa cytoplasmic domain that contains multiple immunoreceptor tyrosine-based inhibitory motifs (ITIMs) or ITIM-like sequences. Alternate splicing generates additional isoforms that carry substituted C-terminal tails of varying lengths and sequences following the ECD or transmembrane segment. Within the ECD, human LMIR3 shares 43 sequence identity with mouse and rat LMIR3. LMIR3 is expressed on the surface of dendritic cells, monocytes, granulocytes, and mast cells as well as on acute myeloid leukemia (AML) blasts. Pervanadate treatment or antibody cross-linking of LMIR3 induces phosphorylation of tyrosine residues in the cytoplasmic domain and the subsequent recruitment of phosphatases SHIP, SHP-1, SHP-2, and the p85 alpha subunit of PI3K. LMIR3 ligation can induce cell death and inhibit signaling through multiple receptors including Fc epsilon RI, LMIR4, SCF R, TLR2, TLR3, and TLR9. In contrast, it enhances TLR4-mediated signaling/cytokine production in mast cells through association with the activating signaling protein FcR gamma. In mouse, a splice variant of LMIR3 (known as DIgR2, with a 7aa insertion in the ECD) inhibits CD4+ T cell activation and in vivo Th1 and CTL responses. LMIR3 is upregulated on monocytes surrounding experimentally-induced spinal cord demyelination and functions as a negative regulator of inflammation in the CNS. Source: Murine myeloma cell line, NS0-derived human LMIR3 (Tyr16-Leu155). SDS-PAGE: 57-62kD, reducing conditions Activity: Measured by its ability to stimulate human T cell proliferation. The ED50 for this effect is typically 0.75-4.5ug/ml. Storage and Stability: Lyophilized and reconstituted products are stable for 6 months after receipt at -20C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer. |
