The invention relates to a chimeric antigen-receptor polypeptide heterodimer comprising two polypeptides, wherein the first contains an extracellular part of the major histocompatibility complex I alpha chain and the second contains a 32-microglobulin domain, or the first contains an extracellular part of the major histocompatibility complex II alpha chain and the second contains a major histocompatibility complex II beta chain. One of the polypeptides further contains a transmembrane domain, a hinge region and an intracellular domain of the T cell receptor alpha chain and the other one contains a transmembrane domain, a hinge region and an intracellular domain of the T cell receptor beta chain, and additionally an antigen-peptide covalently linked to said extracellular MHC domain. The invention further relates to a method for the identification of a TCR recognizable peptide sequence making use of the heterodimer of the invention.
