CD45, previously called LCA (leukocyte common antigen) T200, or Ly5inmice, is member C of t he class 1 (receptorlike) protein tyrosine phosphatase f amily ( PTPRC). It is avaliably glycosylated 180220kD transmembrane proteint hat is abundantly expressed on all nucleated cells of hematopoietic origin. CD45 has several isoforms, expressed according t o cell type, developmental stage and anti- genicexposure. The l ongest form, CD45RABC (called B220 i n mouse) , is expressed on B lymphocyte . The CD45RABC cDNA encodes 1304 amino acids (aa), including a 23 aa signal sequence, a 552 aa extracellular domain containing the splicing region, a cysteinerich region and t wo fibronect in type III domains, a 22 aa transmembrane sequence, and a 707 aa cytoplasmic domain t hat contains two hosphatase domains, D1 and D2. Only D1 has phosphatase activity. CD45R0 is t he shor test form, lackingexons 4,5 and 6 which encode aa32191. It is expressed on memory cells, while intermediate sizes are expressed on other T cells. CD45 has been best studied in T cells, where it determines T cell receptor signaling thresholds. CD45 i s moved intoor out of the immunologicalsynapse (IS) membrane microdomain depending on the relative influence of interaction with the extracellular galectin lattice or the intracellular actin cytoskeleton. Galectin interaction can be finetuned by varying usage of the heavily Oglycosylated spliced regions and sialylation of N-linked carbohydrates. Within the I S, CD45 ephosphorylates and negatively regulates the Src family kinase, Lck . In other leukocytes, CD45 influences differentiation and links immunoreceptor signaling with cytokne secretion and cell survival, partially overlapping in function with DEP1/ CD148. CD45 deletion causes in severe i mmunodeficiency, while pont mutations may be associated with utoimmunedisorders.
Recombinant protein corresponding to Gln24-Lys575 from human CD45 fused to 6-His tag at C-terminal, expressed in NS0 cells (P08575).
Applications:Suitable for use in ELISA. Other applications not tested.
Recommended Dilutions:Optimal dilutions to be determined by the researcher.
Functional Activity:1ug/ml of rhCD45 is captured onto a mouse anti-Polyhistidine antibody coated plate, the concentration of rhGalectin1 that produces 50% of the optimal binding is found to be ~0.35-1.4ug/ml.
Storage and Stability:Lyophilized and reconstituted products are stable for 6 months after receipt 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.
