Recombinant Human CD300LB-Fc Chimera (carrier-free)

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Other Names
CD300 antigen like family member B, Leukocyte mono-Ig-like receptor 5 (LMIR5), CMRF35-like molecule 7 (CLM-7, Clm7), Immune receptor expressed on myeloid cells 3 (IREM-3), Gm253
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Recombinant human CD300LB-Fc Chimera inhibits the anti-human CD3 (Cat. No. 317325) induced proliferation of activated human T cells. The ED50 for this effect is 1 - 5 µg/mL.
  • Human_CD300LB_Fc_CF_RECOM_1_112019
    Recombinant human CD300LB-Fc Chimera inhibits the anti-human CD3 (Cat. No. 317325) induced proliferation of activated human T cells. The ED50 for this effect is 1 - 5 µg/mL.
  • Human_CD300LB_Fc_CF_RECOM_2_112019
    Stability Testing for Recombinant Human CD300LB-Fc Chimera. Human CD300LB-Fc was aliquoted in PBS at 0.2 mg/mL. One aliquot was frozen and thawed four times (4x Freeze/Thaw) and compared to the control that was kept at 4°C (control). The samples were tested for their ability to inhibit anti-human CD3-induced proliferation of activated human T cells. The ED50 for this effect is 1 - 5 µg/mL.
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786904 25 µg 140€
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Human CD300LB is a member of the CD300 family of molecules that have regulatory function in the immune system. The human and mouse families of proteins have seven and nine members, respectively. The human genes are localized on chromosome 17 and the mouse genes in the syntenic region on chromosome 11. The CD300 receptors are type I attached membrane proteins that contain one IgV-like extracellular domain having two disulfide bonds. In addition, CD300LB possesses a positive charged amino acid (Lys) in its transmembrane domain and a short cytoplasmic tail that lacks a signaling motif. Differential regulation in the activation of human and mouse CD300LB has been reported. Mouse CD300LB associates with its adaptor molecules DAP10 (DNAX-activating protein 10) and DAP12 through the positive charged amino acid (Lys) in the transmembrane domain. Studies with transduced bone marrow-derived mast cells have shown that DAP12 plays a primary role in the functions of mouse CD300LB, and DAP12 and DAP10 in the function of human CD300LB. Nevertheless, activation of the human receptor induces cytokine production by bone marrow-derived mast cells even in the absence of DAP12 and DAP10, suggesting the participation of additional adaptors. CD300LB is expressed by myeloid cells and its transduction in bone marrow-derived mast cells induces cell survival, degranulation, cytokine production, and adhesion to the extracellular matrix. Neutrophils release a soluble form of CD300LB through a proteolytic process with possible participation of MMPs and/or ADAM-TS family members. Raw 264.7 cells, but not macrophages, also release soluble CD300LB and this release is induced by lipopolysaccharide (LPS) and it is dose dependent. LPS induces the interaction of CD300LB to TLR4 and drives lethal cytokine responses that boost septic shock.

Product Details
Technical data sheet

Product Details

Human CD300LB, amino acid Iso55 – Tyr188 (Accession # BC028091) was expressed in CHO cells. The carboxy terminus contains an hIgG Fc tag.
Molecular Mass
The 373 amino acid recombinant protein has a predicted molecular mass of approximately 42 kD. The DTT-reduced and non-reduced protein migrates at approximately 50 kD and 100 kD by SDS-PAGE, respectively. The predicted N-terminal amino acid is Iso.
>95%, as determined by Coomassie stained SDS-PAGE.
0.22 µm filtered protein solution is in PBS pH 7.2.
Endotoxin Level
Less than 0.1 EU per µg protein as determined by the LAL method.
10 and 25 µg sizes are bottled at 200 µg/mL. 100 µg and larger sizes are lot-specific and bottled at the concentration indicated on the vial (please contact technical support for concentration, or use our Lookup tool if you have a lot number.)
Storage & Handling
Unopened vial can be stored between 2°C and 8°C for one month, at -20°C for six months, or at -70°C for one year. For maximum results, quick spin vial prior to opening. The protein can be aliquoted and stored at -20°C to -70°C. Stock solutions can also be prepared at 50 - 100 µg/mL in sterile buffer (PBS, HPBS, DPBS, or EBSS) containing carrier protein such as 0.2 - 1% BSA or HSA and stored in working aliquots at -20°C to -70°C. Avoid repeated freeze/thaw cycles.
Recombinant human CD300LB inhibits the anti-human CD3 (Cat. No. 317325)-induced proliferation of activated human T cells; the inhibitory effect was measured using the Deep Blue Cell Viability™ Kit (Cat. No. 424701). The EC50 for this effect is 1 - 5 µg/mL.


Application Notes

BioLegend carrier-free recombinant proteins provided in liquid format are shipped on blue ice. Our comparison testing data indicates that when handled and stored as recommended, the liquid format has equal or better stability and shelf-life compared to commercially available lyophilized proteins after reconstitution. Our liquid proteins are verified in-house to maintain activity after shipping on blue ice and are backed by our 100% satisfaction guarantee. If you have any concerns, contact us at

Antigen Details


Myeloid cell lines, granulocytes, dendritic cells, macrophages, and mast cell.

Activation of mast cells, activation of myeloid cells through TLR4, inflammatory mediator.
DAP12, DAP10
Recombinant human CD300LB inhibits the anti-human CD3 (Cat. No. 317325)-induced proliferation of activated human T cells.
Cell Type
Dendritic cells, Granulocytes, Macrophages, Mast cells, Monocytes
Biology Area
Immunology, Innate Immunity
Molecular Family
CD Molecules, Soluble Receptors
Antigen References
  1. Chung DH, et al. 2003. J Immunol. 171: 6541.
  2. Kumagai H, et al. 2003. Biochem Biophys Res Commun. 307:719.
  3. Yamanishi Y, et al. 2008. Blood. 111: 688.
  4. Yamanishi Y, et al. 2010. J Exp Med. 207:1501.
  5. Yamanishi Y, et al. 2012. J Immunol. 189:1773.
  6. Borrego F. 2013. Blood. 121:1951.
  7. Phongsisay V, et al. 2014. Mol Immunol. 62:169.
  8. Voss OH, et al. 2016. Immunity. 44:1365.
Gene ID
124599 View all products for this Gene ID
View information about CD300LB on

Related FAQs

Does specific activity of a recombinant protein vary between lots?

Specific activity will vary for each lot and for the type of experiment that is done to validate it, but all passed lots will have activity within the established ED50 range for the product and we guarantee that our products will have lot-to-lot consistency. Please conduct an experiment-specific validation to find the optimal ED50 for your system.

Have your recombinants been tested for stability?

Our testing shows that the recombinant proteins are able to withstand room temperature for a week without losing activity. In addition the recombinant proteins were also found to withstand four cycles of freeze and thaw without losing activity.

How do you convert activity as an ED50 in ng/ml to a specific activity in Units/mg?
Use formula Specific activity (Units/mg) = 10e6/ ED50 (ng/mL)
How does the activity of your recombinant proteins compare to competitors?

We quality control each and every lot of recombinant protein. Not only do we check its bioactivity, but we also compare it against other commercially available recombinant proteins. We make sure each recombinant protein’s activity is at least as good as or better than the competition’s. In order to provide you with the best possible product, we ensure that our testing process is rigorous and thorough. If you’re curious and eager to make the switch to BioLegend recombinants, contact your sales representative today!

What is the specific activity or ED50 of my recombinant protein?

The specific activity range of the protein is indicated on the product datasheets. Because the exact activity values on a per unit basis can largely fluctuate depending on a number of factors, including the nature of the assay, cell density, age of cells/passage number, culture media used, and end user technique, the specific activity is best defined as a range and we guarantee the specific activity of all our lots will be within the range indicated on the datasheet. Please note this only applies to recombinants labeled for use in bioassays. ELISA standard recombinant proteins are not recommended for bioassay usage as they are not tested for these applications.

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For research use only. Not for diagnostic use. Not for resale. BioLegend will not be held responsible for patent infringement or other violations that may occur with the use of our products.


*These products may be covered by one or more Limited Use Label Licenses (see the BioLegend Catalog or our website, BioLegend products may not be transferred to third parties, resold, modified for resale, or used to manufacture commercial products, reverse engineer functionally similar materials, or to provide a service to third parties without written approval of BioLegend. By use of these products you accept the terms and conditions of all applicable Limited Use Label Licenses. Unless otherwise indicated, these products are for research use only and are not intended for human or animal diagnostic, therapeutic or commercial use.


BioLegend Inc., 8999 BioLegend Way, San Diego, CA 92121
Toll-Free Phone: 1-877-Bio-Legend (246-5343) Phone: (858) 768-5800 Fax: (877) 455-9587

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