FITC Conjugated Human CD45RA Recombinant Mouse Monoclonal Antibody [PSH04-97]

The CD45 protein family consists of multiple members that are all products of a single complex gene. This gene contains 34 exons, producing a massive protein with extracellular and cytoplasmic domains that are both unusually large. Exons 4, 5, and 6 (corresponding to protein regions A, B, and C) are alternatively spliced to generate up to eight different protein products featuring combinations of zero, one, two, or all three exons. CD45's large extracellular domain is highly glycosylated, and these eight isoforms allow wide variation in the structure of its side chains. The isoforms affect the protein's N-terminal region, which extends linearly out from the cell and bears the O-linked glycan chains. CD45 isoforms show cell-type and differentiation-stage specific expression, a pattern which is quite well conserved in mammals. These isoforms are often used as markers that identify and distinguish between different types of immune cells. Naive T lymphocytes are typically positive for CD45RA, which includes only the A protein region. Activated and memory T lymphocytes express CD45RO, the shortest CD45 isoform, which lacks all three of the A, B, and C regions. This shortest isoform facilitates T cell activation. CD45R (also known as CD45RABC) contains all three possible exons. It is the longest protein and migrates at 200 kDa when isolated from T cells. B cells also express CD45R with heavier glycosylation, bringing the molecular weight to 220 kDa, hence the name B220 (B cell isoform of 220 kDa).