The typical structure of a CAR molecule includes a single chain variable fragment (scFv), a spacer, a transmembrane domain (TM) and an intracellular signaling domain. The scFv is derived from monoclonal antibody (mAb), which can specifically recognize the target protein on tumor surface and subsequently transduct activation signal into chimeric antigen receptor t-cells. https://www.creative-biolabs.com/car-t/cellrapeutics-chimeric-antigen-receptor-car-technology.htm