CD45 and the immune response.

Abstract

CD45 is a major transmembrane glycoprotein expressed on all nucleated hematopoietic cells. Eight isoforms of CD45 are distributed through the immune system according to cell type and degree of cellular differentiation. Heterogeneity among the isoforms is found entirely in the extracellular domain, arising from the differential splicing of up to four exons of a single gene. The control of isoform expression suggests that the extracellular domain may participate in protein-protein interactions with isoform-specific ligands. The intracellular domain of CD45 is large (approximately 700 amino acids), identical for all isoforms, and highly conserved across species. Two nonidentical intracellular sequences of about 240 amino acids that are homologous with a tyrosine phosphatase consensus sequence have been identified. Studies with purified CD45 have shown that all isoforms possess enzymatic activity in in vitro assays. In several T and B cell lines and in natural killer cells, it appears that CD45 is required for optimal signal transduction after stimulation through a number of surface receptors. Although an in vivo substrate has not been identified conclusively, one model suggests that CD45 functions to dephosphorylate a negative-regulatory tyrosine residue on one or more protein tyrosine kinases involved in receptor-mediated second messenger formation. In T cells, the src family kinases, lck and fyn, are candidates for this regulated kinase. In this review, some of the structural and functional aspects of CD45 and its role in signal transduction in the immune system are discussed.

Efficient Total Synthesis of Pulchellalactam, a CD45 Protein Tyrosine Phosphatase Inhibitor

“…Recently, a receptor-like transmembrane protein tyrosine phosphatase, CD45, has been shown to play a crucial role in activation of both B and T cells. − CD45 therefore represents a therapeutic target for various autoimmune and chronic anti-inflammatory diseases. ,− Currently, there are few readily available potent inhibitors of CD45 protein tyrosine phosphatase other than vanadate. Thus, a great need remains for the discovery of selective and potent CD45 inhibitors.…”

Spectral Analysis of ATP-Dependent Mechanical Vibrations in T Cells

“…In order to test this hypothesis we first highlighted the cell membrane via fluorescent staining of CD45, an abundant surface glycoprotein in T cells ( Donovan and Koretzky, 1993 ). Then we conducted fast and repetitive line-scans across the cell membrane at its apparent mid-section by confocal scanning microscopy ( Figure 6B ).…”

CD8+T Cell-Related Gene Biomarkers in Macular Edema of Diabetic Retinopathy

“…IKZF1 is a candidate pathogenic gene for type 1 diabetes, which is related to its susceptibility (63). The PTPRC gene, which encodes type C protein tyrosine phosphatase receptor, also known as CD45, is expressed in all hematopoietic nucleated cells (64). CD45 regulates the interaction between T cells and macrophages via its ligand galactose lectin, which causes the elevation of cytotoxic T lymphocyte-associated protein 4 with CD8+T cell tolerance (65).…”