Platelet Glycoprotein Ib alpha, Recombinant, Human (PGIb alpha)
Artikelnummer:
USB-P4259-12
Hersteller Artikelnummer:
P4259-12
Alternativnummer:
USB-P4259-12-50
Hersteller:
US Biological
Kategorie:
Molekularbiologie
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. A DNA sequence encoding the extracellular domain of human GPIb A (His17-Leu505, UniProt/Accession: P07359) was fused with a six-histidine tag at the C-terminus. The protein was expressed in NS0 cells line. Calculated 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 Terminal Sequence Analysis: His 17 SDS-PAGE: ~95-120kD, reducing conditions Activity: Measured by its binding ability in a functional ELISA. Recombinant Human CD42b/GPIb alpha is immobilized at 0.5ug/ml (100ul/well), the concentration of recombinant human vWF-A2 that produces 50% optimal binding response is ~6-36ng/ml in the presence of ristocetin. Storage and Stability: Lyophilized and reconstituted products may be stored at -20C. Stable for 6 months after receipt at -20C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
