GRAB(DA3h) is a genetically encoded fluorescent sensor for dopamine (high affinity). It is a G-protein-coupled receptor activation-based ('GRAB') sensor based on the dopamine receptor encoded by the Bos taurus DRD1 gene (VGNC:28207); the third intracellular loop of DRD1 has been replaced with a circularly permuted form of EGFP (cpEGFP) (flanked by linkers) and a number of additional mutations have also been introduced during optimization of the sensor. Dopamine-dependent conformational changes in the receptor result in a change in fluorescence of the conformationally sensitive cpEGFP (PMID:38036855).