Integrin alphaLbeta2 is one of three beta2 integrin adhesion proteins. The non-covalent heterodimer of 180kD aL/CD11a and 95kD b2/CD18 integrin subunits is expressed on virtually all leukocytes. The ligand binding site of LFA-1 is in the N-terminal head region, formed by an interaction of the vWFA (I, I-like) domains from each subunit, and the aL betapropeller structure. The aL subunit contains domains termed thigh, calf-1 and calf-2, while the b2 subunit contains a PSI region and four cysteine-rich I-EGF folds. Each subunit has a transmembrane sequence and a short cytoplasmic tail connected to the cytoskeleton. Upon activation by “inside-out” signaling, clustering, or Mg2+ or Mn2+ binding to metal ion-dependent adhesion sites within the vWFA domains, the molecule unfolds from its inactive, “closed” conformation to expose ligand binding sites. Active aLb2 binds ICAM-1/CD54, ICAM-2, ICAM-3 and JAM-A. The adhesion stabilizes interactions between T cells and antigen-presenting cells, decreases the T cell activation threshold and facilitates leukocyte transendothelial migration to sites of inflammation. A constitutively active construct severely impairs immune responses, demonstrating that both activation and de-activation are important. Mutations of b2, especially in the vWFA domain, cause leukocyte adhesion deficiency (LAD-1) and susceptibility to bacterial infections. The 1088aa human aL/CD11b is 73-74% aa identical to mouse and rat, and 79-80% aa identical to bovine, porcine, ovine, goat and canine. The 678aa human b2/CD18 shares 81-83% aa sequence identity with mouse, rat, bovine, canine, goat, ovine and porcine b2 ECD. A second human aL isoform has 53 aa inserted after aa 954 in the ECD. The 678 aa human b 2/CD18 ECD shares 81-83% aa sequence identity with mouse, rat, bovine, canine, goat, ovine and porcine b2 ECD.
Source:Human Integrin alpha L (Tyr26-Met1089) acidic tail, ~121.7kD, Accession #P20701Human Integrin beta2 (Gln23-Asn700) basic tail, ~79kD, Accession #P05107 expressed in Chinese hamster ovary (CHO) cells.
Molecular Mass:Based on N-terminal sequencing, the recombinant human Integrin aL subunit starts at Tyr 26 and has a calculated molecular mass of approximately 121.7kD. The N-terminal sequence of the b2 subunit was blocked, suggesting that the b2 subunit may start at the predicted Gln 23 and has a calculated molecular mass of approximately 79kD. As a result of glycosylation, the recombinant proteins migrate as approximately 160 and 100kD protein bands in SDS-PAGE under reducing conditions.
SDS-PAGE:~160kD and 100kD under reducing conditions. Predicted MW: 121.7kD (Integrin aL), 79kD (Integrin b2)
Biological Activity:Measured by the ability of the immobilized protein to support the adhesion of CHO cells transfected with human ICAM-1. When 5x10e4 cells/well are added to Integrin aLb2-coated plates (5ug/ml, 100ul/well), 60-80% of the cells will adhere after 1 hour at 37°C in the presence of 1mM MnCl2.
Storage and Stability:Lyophilized powder may be stored at -20°C. Stable for 12 months at -20°C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store at -20°C. 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.
仕様
Size：50ug
Source Antigen：Chinese hamster ovary (CHO) cells
Grade：Highly Purified
Purity：≥95%, as determined by SDS-PAGE and visualized by silver stain. Endotoxin: ≤1EU/ug (LAL).
Form：Supplied as a lyophilized powder from PBS, pH 7.2. Reconstitute with 500ul sterile PBS.
