CD197, also known as CCR7, is a protein encoded by the CCR7 gene in humans and belongs to the G protein-coupled receptor family. It is a transmembrane protein with seven transmembrane domains, which is coupled with heterotrimeric G proteins to transduce signals downstream through various signaling cascades. CCR7 binds to two ligands: the chemokines CCL19 and CCL21. The main function of CCR7 is to guide immune cells to immune organs such as lymph nodes, thymus, and spleen by detecting specific chemokines secreted by these tissues. It is expressed on adaptive immune cell types, including thymocytes, naive T and B cells, regulatory T cells, central memory lymphocytes, and dendritic cells. CCR7 plays a crucial role in the maturation of dendritic cells and the trafficking of T cells within secondary lymphoid organs.