Recombinant Human B7-H3 His-tag Avi-tag Protein, CF

Biotinylated long-form B7-H3 (4Ig)/B7-H3b
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Recombinant Human B7-H3 His-tag Avi-tag Protein, CF Binding Activity
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Recombinant Human B7-H3 His-tag Avi-tag Protein, CF Summary

>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
Endotoxin Level
<1.0 EU per 1 μg of the protein by the LAL method.
Measured in a cell proliferation assay using mouse CD4+ cells in the presence of anti-CD3. The ED50 for this effect is 3-12 μg/mL. Measured by its binding ability in a functional ELISA. When Human B7-H3 Antibody (Catalog # AF1027) is immobilized at 1.0 μg/mL, 100 μL/well, the concentration of Biotinylated Recombinant Human B7‑H3 His-tag Avi-tag (Catalog # AVI2318) that produces 50% of the optimal binding response is approximately 3 -15 ng/mL.
Human embryonic kidney cell, HEK293-derived human B7-H3 protein
Human B7-H3
Accession # Q5ZPR3-1
HHHHHH Avi-tag
Accession #
N-terminal Sequence
Structure / Form
Biotinylated via Avi-tag
Predicted Molecular Mass
49 kDa
70-90 kDa, under reducing conditions

Product Datasheets

Carrier Free

What does CF mean?

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.

What formulation is right for me?

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.


Formulation Lyophilized from a 0.2 μm filtered solution in PBS with Trehalose.
Reconstitution Reconstitute at 200 μg/mL in PBS.
Shipping The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 12 months from date of receipt, -20 to -70 °C as supplied.
  • 1 month, 2 to 8 °C under sterile conditions after reconstitution.
  • 3 months, -20 to -70 °C under sterile conditions after reconstitution.

Data Images

Binding Activity View Larger

When Human B7-H3 Antibody (Catalog # AF1027) is immobilized at 1.0 µg/mL, 100 µL/well, the concentration of Biotinylated Recombinant Human B7-H3 His-tag Avi-tag (Catalog # AVI2318) that produces 50% of the optimal binding response is approximately 3-15 ng/mL.

SDS-PAGE View Larger

2 μg/lane of Recombinant Human B7-H3 His-tag Avi-tag (Catalog # AVI2318) was resolved with SDS-PAGE under reducing (R) and non-reducing (NR) conditions and visualized by Coomassie® Blue staining, showing bands at 70-90 kDa.

Reconstitution Calculator

Reconstitution Calculator

The reconstitution calculator allows you to quickly calculate the volume of a reagent to reconstitute your vial. Simply enter the mass of reagent and the target concentration and the calculator will determine the rest.


Background: B7-H3

Human B7 homolog 3 (B7-H3) is a member of the B7 family of immune proteins that provide signals for the regulation of immune responses (1 - 3). Other family members include B7-1, B7-2, B7-H1/PD-L1, B7-H2, and PD-L2. B7 family proteins are type I transmembrane immunoglobulin (Ig) superfamily members that contain extracellular Ig V‑like and Ig C‑like domains with a short cytoplasmic tail. Among the family members there is about 20 - 40% amino acid (aa) sequence identity. B7-H3 was initially reported to be a 316 aa type I transmembrane precursor protein that contained a signal sequence, an extracellular region with one V‑type and one C‑type Ig domain, a transmembrane segment and a short cytoplasmic tail (1). Subsequent studies have identified a second 110 kDa form whose precursor is 534 aa in length. Termed 4IgB7-H3 or B7-H3b, this molecule has two additional Ig-like domains (one V‑type and one C‑type) and shows a ubiquituous expression pattern (4, 5). It would appear that the human 4Ig form is the principal, if not the only form of B7-H3 (5). Its precursor contains a 26 aa signal sequence, a 435 aa extracellular region, a 31 aa transmembrane domain, and a 42 aa cytoplasmic tail. The four Ig-like domains alternate between V‑type and C‑type, and apparently are the consequence of a V‑C type tandem duplication (4, 5). B7-H3b is expressed on dendritic cells as well as activated T, B and NK cells (5). The mouse gene differs from that of human in that it cannot code for four Ig-like domains; only a V‑type:C‑type pair (4). Human B7-H3b binding to an undefined receptor has shown to be inhibitory to NK cells and cytokine release (6). It also seems to be required for late stage osteoblast differentiation (7).

  1. Chapoval, A.I. et al. (2001) Nat. Immunol. 2:269.
  2. Sharpe, A.H. and G.J. Freeman (2002) Nat. Rev. Immunol. 2:116.
  3. Coyle, A. and J.Gutierrez-Ramos (2001) Nat. Immunol. 2:203.
  4. Sun, M. et al. (2002) J. Immunol. 168:6294.
  5. Steinberger, P. et al. (2004) J. Immunol. 172:2352.
  6. Prasad, D.V.R. et al. (2004) J. Immunol. 173:2500.
  7. Suh, W-K. et al. (2004) Proc. Natl. Acad. Sci. USA 101:12969.
Long Name
B7 Homolog 3
Entrez Gene IDs
80381 (Human); 102657 (Mouse); 315716 (Rat); 102131295 (Cynomolgus Monkey)
Alternate Names
B7H3; B7-H3; B7H34Ig-B7-H3; B7-H3B7 homolog 3; CD276 antigen; CD276 molecule; CD276; Costimulatory molecule


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