PDCD1 Gene (PD-1): Function, Mutations, and Clinical Relevance | Biomedical Resource

The PDCD1 gene encodes programmed cell death protein 1 (PD-1), a type I transmembrane glycoprotein of the immunoglobulin superfamily. PD-1 is an immune checkpoint receptor expressed on activated T cells, B cells, and myeloid cells. It negatively regulates immune responses by binding to its ligands PD-L1 (CD274) and PD-L2 (PDCD1LG2), thereby inhibiting T-cell activation, cytokine production, and cytotoxicity. PD-1 plays a critical role in maintaining peripheral tolerance and preventing autoimmunity, but it is also exploited by tumors to evade immune surveillance. The PDCD1 gene is located on chromosome 2q37.3 and spans approximately 9.2 kb, containing 5 exons. Alternative splicing produces multiple isoforms, including soluble forms. PD-1 is a key target for cancer immunotherapy, with monoclonal antibodies (e.g., pembrolizumab, nivolumab) blocking its interaction with ligands to enhance anti-tumor immunity.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• PD-1 signaling pathway (Reactome: R-HSA-389948)

• Programmed cell death 1 (PD-1) signaling (KEGG: hsa05235 - PD-L1 expression and PD-1 checkpoint pathway in cancer)

• T cell receptor signaling pathway (KEGG: hsa04660)

• Immune checkpoint pathway (WikiPathways: WP4486)

PD-1 (Programmed cell death protein 1) is a 288-amino acid type I transmembrane protein with an extracellular N-terminal immunoglobulin V-like domain, a transmembrane domain, and a cytoplasmic tail containing an immunoreceptor tyrosine-based inhibitory motif (ITIM) and an immunoreceptor tyrosine-based switch motif (ITSM). Upon ligand binding (PD-L1/PD-L2), PD-1 recruits SHP-2 phosphatase via ITSM, dephosphorylating TCR signaling molecules (e.g., ZAP70, CD3ζ), thereby inhibiting T-cell activation, proliferation, and cytokine secretion. PD-1 is expressed on activated T cells, B cells, natural killer T cells, and monocytes. Its expression is induced by TCR stimulation and cytokines such as IL-2, IL-7, and IL-15. PD-1 plays a crucial role in peripheral tolerance and is a major mediator of T-cell exhaustion in chronic infections and cancer. The protein is a validated therapeutic target; anti-PD-1 antibodies (e.g., pembrolizumab, nivolumab) are used in oncology to reinvigorate anti-tumor immunity.