Recombinant Human B7-H3(4Ig)/B7-H3b Protein (C09-1190-532)

Purity:>95%, by SDS-PAGE visualized with Coomassie® Blue StainingDescription: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. 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. 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. It would appear that the human 4Ig form is the principal, if not the only form of B7-H3. 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. B7-H3b is expressed on dendritic cells as well as activated T, B and NK cells. 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. Human B7-H3b binding to an undefined receptor has shown to be inhibitory to NK cell illing and cytokine release. It also seems to be required for late stage osteoblast differentiation. Specifications and Purity: Animal Free, >95% (SDS-PAGE), Active, 293F cell, His tag, 29-461 aa.