Platelet Glycoprotein Ib alpha, Recombinant, Human (PGIb alpha)

Platelet glycoprotein Ib alpha chain (GPIb a), also known as CD42ba, is a 145kD type I transmembrane protein that is a member of the leucine-rich repeat (LRR) family of ligand binding proteins.1-3 It is expressed by platelets as the ligand-binding subunit of the platelet GPIb-IX-V complex.4 Human GPIb a contains a 16 amino acid (aa) signal sequence, a 489 aa extracellular domain (ECD), a 21-aa transmembrane domain, and a 100 aa cytoplasmic region. The ECD contains 8 LRRs, with # 2, 3 and 4 having been demonstrated to regulate shear-dependent adhesion to von Willebrand factor (vWF).5, 6 The LRRs are followed by a thrombin-binding anionic region that includes three sulfated tyrosines, a sialomucin domain with N- and O-linked carbohydrates, and two cysteines near the membrane that allow dimerization with GP1bb.1-6 Four human isoforms with 1 to 4 repeats of aa 398-411 within the sialomucin domain of mature GPIb a are known to exist but have unknown significance.7 The ECD of human GPIb a shares 48-51% aa identity with mouse, rat, bovine and canine GPIb a. The metalloproteinase TACE/ADAM17 constitutively and inducibly cleaves GPIb a, between Gly 480 and Val 481. This releases a soluble form called glycocalicin that circulates at ~2 ug/mL.8, 9 GPIb a binding to ligands such as thrombin, kininogen, and coagulation factors XI and XII helps to initiate platelet activation and coordinate the coagulation cascade.1, 10-12 Binding of GPIb a to vWF or thrombospondin in the plasma or matrix, vWF or P-selectin on endothelial cells, or the integrin aMb2 (MAC-1) on myeloid cells, controls response to vascular injury.\n\nA DNA sequence encoding the extracellular domain of human GPIb A (His 17-Lys 505; Accession # P07359) was fused with a six-histidine tag at the C-terminus. The protein was expressed in NS0 cells line.\n\nCalculated molecular mass of ~ 54.7kD. As a result of glycosylation, recombinant human GPIb a migrates as an ~ 95-120kD protein in SDS-PAGE under reducing conditions.\n\nN Terminal Sequence Analysis:\n His 17\n\nSDS-PAGE:\n~95-120kD, reducing conditions\n\nActivity: \nMeasured by its

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SPECIFICATIONS

Catalog Number

P4259-12

Size

50ug

Form

Supplied as a lyophilized powder in PBS. Reconstitute with PBS to (same/more than)100ug/ml.

Purity

(same/more than)90%, as determined by SDS-PAGE under reducing conditions and visualized by silver stain. Endotoxin: (same/less than)1.0EU/ug (LAL)

References

1. Andrews, R.K. et al., 2007, Arterioscler. Thromb. Vasc. Biol. 27:1511. 8. Gardiner, E.E. et al., 2007, J. Thromb. Haemost. 5:1530. 2. Lopez, J.A. et al., 1987, Proc. Natl. Acad. Sci. USA 84:5615. 9. Beer, J.H. et al., 1994, Blood 83:691. 3. Wenger, R.H. et al., Biochem. Biophys. Res. Commun. 156:389. 10. Adam, F. et al., 2003, Eur. J. Biochem. 270:2959. 4. Luo, S-Z. et al., 2007, Blood 109:603. 11. Baglia, F.A. et al., 2004, J. Biol. Chem. 279:49323. 5. Uff, S. et al., 2002, J. Biol. Chem. 277:35657. 12. Bradford, H.N. et al., 2000, J. Biol. Chem. 275:22756. 6. Shen, Y. et al., 2006, J. Biol. Chem. 281:26419. 13. Wang, Y. et al., 2005, Circulation 112:2993. 7. Ishida, F. et al., 1995, Blood 86:1356. 14. Othman, M. et al., 2005, Blood 105:4330.