PDCD1 recombinant proteins refer to engineered versions of the PD-1 protein, also known as Programmed Cell Death Protein 1. PD-1 is an immune checkpoint receptor expressed on the surface of various immune cells, including T cells. It plays a crucial role in regulating immune responses by inhibiting T cell activation, which helps maintain self-tolerance and prevent autoimmunity. However, PD-1 can also be exploited by tumors to evade immune surveillance. Recombinant PDCD1 proteins are essential for research into immune regulation, cancer immunotherapy, and the development of checkpoint inhibitors.

Structure and Function

• PD-1 is a transmembrane protein with an extracellular domain that binds to its ligands, PD-L1 and PD-L2. It contains an immunoreceptor tyrosine-based inhibitory motif (ITIM) and an immunoreceptor tyrosine-based switch motif (ITSM) in its intracellular domain, which are involved in signaling pathways that inhibit T cell activation.
• Recombinant PD-1 proteins typically include the extracellular domain, which is crucial for ligand binding, or full-length proteins for functional studies.

Production

• Recombinant PD-1 proteins are produced in various expression systems, such as E. coli, yeast, insect cells, or mammalian cells, depending on the need for proper folding and post-translational modifications.
• The gene encoding PD-1 is cloned into an expression vector, expressed, and purified using affinity chromatography techniques, often with tags like His-tag or GST-tag.

Applications

• Cancer Research: Recombinant PD-1 proteins are used to study the interaction between PD-1 and its ligands (PD-L1/PD-L2), which is critical for understanding how tumors evade immune detection.
• Immunotherapy Development: These proteins are employed in the development and testing of immune checkpoint inhibitors (e.g., anti-PD-1 antibodies) designed to block the PD-1 pathway and enhance anti-tumor immune responses.
• Diagnostics: PD-1 recombinant proteins are used in assays to detect and quantify PD-1 expression and interactions, aiding in the assessment of immune checkpoint inhibition in clinical and research settings.
• Basic Research: They are essential for elucidating the mechanisms of immune regulation, studying T cell exhaustion, and exploring new therapeutic strategies targeting the PD-1 pathway.

Validation and Quality Control

• Validation of recombinant PD-1 proteins includes confirming their identity and purity using techniques such as SDS-PAGE, Western blotting, and mass spectrometry.
• Functional assays, such as binding studies with PD-L1/PD-L2 or activity assays in cell-based systems, are conducted to ensure that the recombinant proteins are biologically active and suitable for their intended applications.