The proposed connections were confirmed by synthetic lethal interactions, and with human homologues of the THO proteins. Hurt and colleagues named the combined complex the transcription–export or TREX complex, and found that proteins in the complex could be tracked by chromatin immunoprecipitation as they moved along a transcribed gene with RNA polymerase.
Mutants lacking a THO component had an mRNA export defect, but Hurt does not think that transcripts get posted directly from a gene into a nuclear pore complex. Transcription occurs throughout the nucleoplasm, and TREX factor binding at these sites may simply allow nuclear pores to capture mRNA–protein complexes after they diffuse away from these sites. ▪