TdTomato is a widely used fluorescent protein which is typically expressed fused with a protein of interest, allowing the fusion partner to be visualized in a variety of experimental contexts. The prototype for this family is Green Fluorescent Protein (GFP) originally isolated from the jellyfish Aequorea victoria but homologues have now been found in many species. GFP and several other fluorescent proteins were engineered in the labs of Roger Y. Tsein and others to produce a wide variety of novel reagents with enhanced and/or altered fluorescence properties and/or altered protein binding properties. Tomato was developed from DsRed, a protein originally found in a Discosoma coral. GFP and the other fluorescent proteins are all based on a compact 11 strand β-barrel structure of about 27kDa molecular size. TdTomato contains two of these fluorescent moieties in tandem, which is what the "td" refers to. This was done to increase the fluorescence emission of tdTomato fusion proteins. The emission of tdTomato peaks at 580nm which is red to human eyes, explaining the "Tomato" part of the name. We release a new monoclonal antibody raised against recombinant tdTomato, MCA-6F12. This antibody can be used to verify the expression of tdTomato fusion proteins by western blotting and to amplify the tdTomato signal in transfected and transduced cells in sectioned material. TdTomato is closely related to mCherry, also derived from DsRed. Alignment of the protein sequences of the two with Clustal Omega gives an identity score of 86.64%. We document that MCA-6F12 also recognizes mCherry and have localized the MCA-6F12 epitope to amino acids 151-170 of mCherry and 147-166 of tdTomato.
