In the excellence clusters, we had developed a system in which the interaction of a modified T cell receptor (TCR) with an engineered ligand can be controlled by light. In this system the TCR was fused to the Phytochrome B interacting factor PIF and GFP, resulting in the GFP-PIF-TCR. Although the GFP allows visualization of the TCR, it prevents the use of GFP-based readouts. In this publication we have engineered the SNAP-PIF-TCR that is non-fluorescent and show that it can be combined with a GFP-based NF-AT reporter system.