• Purity

  >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.

• Endotoxin Level

  <0.10 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its binding ability in a functional ELISA. When 1 μg/mL of rhG6b/Fc Chimera is captured by a goat anti-human IgG Fc Chimera coated plate, the concentration of biotinylated heparin that produces 50% of the optimal binding response is found to be approximately 10-40 ng/mL.

• Source

  Chinese Hamster Ovary cell line, CHO-derived

  Human G6b (Asn18-Gln142) Accession # O95866	IEGRMD	Human IgG1 (Pro100-Lys330)
  N-terminus		C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Asn18

• Structure / Form

  Disulfide-linked homodimer

• Predicted Molecular Mass

  40.0 kDa (monomer)

• SDS-PAGE

  45-55 kDa under reducing conditions

Background: G6b

G6b is a type I transmembrane glycoprotein in the immunoglobulin superfamily that is encoded within the human class III major histocompatibility complex (1-3). It is expressed mainly on platelets, and has also been detected on megakaryocytes and the human cell line K562 (2-5). Crosslinking of G6b inhibits agonist-stimulated platelet aggregation and activation (5). The 241 amino acid (aa) human G6b isotype B (G6b-B) contains a 17 aa signal sequence, a 125 aa extracellular domain with one V-type Ig-like domain and one N-linked glycosylation site, a 21 aa transmembrane sequence and a 78 aa cytoplasmic sequence with two ITIM inhibitory motifs and a SH3 binding site (1, 2). Phosphorylation at Y211 within the first ITIM is required for interaction with SHP adaptor/tyrosine phosphatase proteins (2, 3). Of several described isoforms, all are identical within aa 22-136, which includes most of the extracellular domain. One contains an alternate signal sequence, while at least two lack a transmembrane sequence and are secreted (2). At least two others, including G6b-A, express alternate C-termini that lack the ITIM motifs. Of the known isoforms, G6b-A and G6b-B predominate in platelets. It is possible that G6b-A may be paired with and control inhibition by G6b-B (4). Heparin interacts with the G6b extracellular domain with high-affinity and may contribute to G6b activity or adhesion to extracellular matrix (6).

• References:

1. Ribas, G. et al. (1999) J. Immunol. 163:278.

2. DeVet, E. C. J. M. et al. (2001) J. Biol. Chem. 276:42070.

3. Senis, Y. A. et al. (2007) Mol. Cell. Proteomics 6:548.

4. Macaulay, I. C. et al. (2007) Blood 109:3260.

5. Newland, S. A. et al. (2007) Blood 109:4806.

6. DeVet, E. C. J. M. et al. (2005) FEBS Lett. 579:2355.

• Long Name:

  Glycoprotein VI [Platelet]

• Entrez Gene IDs:

  80739 (Human); 114763 (Mouse); 406865 (Rat)

• Alternate Names:

  C6orf25; chromosome 6 open reading frame 25; G6b; immunoglobulin receptor; MGC142279; MGC142281; NG31; protein G6b