PD-1 Fc

Programmed cell death protein 1 (PD-1), or CD279, is a type I inhibitory transmembrane receptor of the CD28 receptor family that, along with its B7 family ligands, programmed death ligand 1 (PD-L1) and programmed death ligand 2 (PD-L2), belongs to the immunoglobulin superfamily. While other CD28 family members are expressed predominantly in T cells, PD-1 is widely expressed and found in multiple lymphocytes including T cells, B cells, myeloid, and NKT cells upon activation. PD-1 is a negative regulator of immune response, and is referred to as an inhibitory immune checkpoint molecule. Ligation with PD-L1 or PD-L2 results in inhibited activation, proliferation, and cytokine secretion (e.g. IFN-gamma, IL-10) in T cells, ultimately dampening immune response. Despite the strong homology between PD-L1 and PD-L2, each ligand appears to display distinct lymphokine expression patterns and potency. Blockage of PD-1 ligation by monoclonal antibodies has been proven to be an effective anti-tumor treatment by allowing the immune response to remain active and attack the tumorigenic cells that otherwise would have escaped detection. PD-1 and its ligands have been implicated in numerous autoimmune diseases, inflammatory liver disease and cancers. The naturally occurring human PD-1 monomer consists of a 150 amino acid extracellular domain, a 21 amino acid transmembrane domain, and a 97 amino acid cytoplasmic domain. The CHO cell-derived Recombinant Human PD-1 Fc is a glycosylated, disulfide-linked homodimer of 501 amino acid residues whose monomer consists of the 268-amino-acid length mature PD-1 sequence fused to the 231-amino-acid length Fc portion of human IgG1 by two glycines. The calculated molecular weight of monomeric CHO cell-derived Recombinant Human PD-1 Fc is 55.3 kDa, however, due to glycosylation, it migrates at an apparent molecular weight of approximately 180-200 kDa by SDS-PAGE analysis under non-reducing conditions.