• Purity

  >90%, by SDS-PAGE under reducing conditions and visualized by silver stain

• Endotoxin Level

  <0.01 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by the ability of the immobilized protein to induce pro-MMP-9 secretion by NHLF human normal lung fibroblasts The ED    ₅₀ for this effect is 2.5-10 µg/mL.    
     Optimal dilutions should be determined by each laboratory for each application.  

• Source

  Mouse myeloma cell line, NS0-derived

  Human Osteoactivin (Lys23 - Asn486) Accession #NP_002501	IEGRMD	Human IgG1 (Pro100 - Lys330)
  N-terminus		C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Lys23

• Structure / Form

  Disulfide-linked homodimer

• Predicted Molecular Mass

  78.6 kDa (monomer)

• SDS-PAGE

  115-125 kDa, reducing conditions

Background: Osteoactivin/GPNMB

Osteoactivin (also GPNMB and DC-HIL) is a variably glycosylated 75 - 125 kDa member of the NMB/pMEL-17 family of molecules. It is found in multiple subcellular sites, but is most often associated with the endosomal/lysosomal compartment (1, 2, 3). Human Osteoactivin is a 560 amino acid (aa) type I transmembrane protein. Its precursor contains a 21 aa signal sequence, a 465 aa luminal/extracellular domain, a 21 aa transmembrane segment and a 53 aa cytoplasmic tail (4, 5). The luminal region contains an N-terminal heparin-binding motif (aa 23 - 26), multiple glycosylation sites, an RGD motif (aa 64 - 66) and an 88 aa PKD domain (aa 240 - 327). The intracellular tail has an ITAM (Y-x-x-I) and lysosomal targeting (L-L) motif (4, 5). The extracellular/luminal region shares 74% and 77% aa identity with the equivalent regions in mouse and canine, respectively. Multiple isoforms would appear to exist. There is one alternate splice form known that shows a 12 aa insert between aa 339 - 340 (6). An addtional 206 aa isoform shows a mutation at position # 181 that results in a 26 aa substitution for the C-terminal 380 amino acids (7, 8). This has the potential to be soluble and may represent a counterpart to a secreted isoform of rat Osteoactivin (9). Cells known to express Osteoactivin include macrophages/Kupffer cells, fibroblasts, osteoblasts, myeloid dendritic cells, retinal pigment epithelial cells and melanocytes, plus fetal chondrocytes and stratum basale keratinocytes (3, 4, 5, 10, 11, 12). In mice, Osteoactivin is reported to bind to heparan sulfate-proteoglycan, possibly on the surface of endothelial cells and may also interact with integrins (13). It also appears to act as an inflammatory suppressor gene, as its expression downregulates the macrophage inflammatory response by inhibiting IL-6 and IL-12p40 production (3).

• References:

1. Bachner, D. et al. (2002) Gene Exp. Patterns 1:159.

2. Safadi, F.F. et al. (2002) J. Cell. Biochem. 84:12.

3. Ripoll, V.M. et al. (2007) J. Immunol. 178:6557. 

4. Owen, T.A. et al. (2003) Crit. Rev. Eukaryot. Gene Expr. 13:205. 

5. Weterman, M.A.J. et al. (1995) Int. J. Cancer 60:73. 

6. Kuan, C-T. et al. (2006) Clin. Cancer Res. 12:1970. 

7. Lennerz, V. et al. (2005) Proc. Natl. Acad. Sci. USA 102:16013.

8. Genbank Accession # AAH11595.

9. Abdelmagid, S.M. et al. (2007) J. Cell. Physiol. 210:26.

10. Haralanova-Ilieva, B. et al. (2005) J. Hepatol. 42:565.

11. Ahn, J.H. et al. (2002) Blood 100:1742.

12. Anderson, M.G. et al. (2002) Nat. Genet. 30:81.

13. Shikano, S. et al. (2001) J. Biol. Chem. 276:8125.

• Long Name:

  Glycoprotein Non-Metastatic Melanoma Protein B

• Entrez Gene IDs:

  10457 (Human); 93695 (Mouse)

• Alternate Names:

  DC-HIL; glycoprotein (transmembrane) nmb; glycoprotein NMB; GPNMB; HGFIN; HGFINglycoprotein nmb-like protein; NMBosteoactivin; Osteoactivin; Transmembrane glycoprotein HGFIN; transmembrane glycoprotein NMB