Drug targets a biomolecule that can directly bind to drugs and then react. Generally, the target refers to a protein, which is related to the cause of disease. The focus of the target began with focusing on tumors, and then began to spread to various fields. CD152/CTLA-4 protein is a common target in medicine.

CD152, also known as cytotoxic T-lymphocyte-associated protein 4(CTLA-4), belongs to the CD28 family member, it is a homodimer, and the extracellular region has one V-like region of IgSF, is a class of immunoglobulins expressed on the surface of already activated T cells. CD152 transmits inhibitory signals to T cells. CD152 is a common immune checkpoint molecule with a close association with CD28, but CD152 and CD28 have different roles in the body's immune response. In contrast to CD28, CD152 is mainly present in the intracellular vesicles. CD152 binds to CD80 and CD86 with higher affinity and is able to block ligands binding to CD28. Subsequently, the binding-generated complexes will be transported into the cytoplasm and hydrolyzed by lysosomes, ultimately preventing T-cell activation.

Fig 1: Shared interactions between CD28 and CTLA-4 family members. ( Reference source: Gardner D, Jeffery LE, Sansom DM. Understanding the CD28/CTLA-4 (CD152) pathway and its implications for costimulatory blockade. Am J Transplant. 2014 Sep;14(9):1985-91.)