CID is a domain on higher eukaryotic germinal-cent associated nuclear protein, or GANP, that binds to the transcription and mRNA export factor ENY2. The complex of these two proteins forms part of the TREX-2 complex that links transcription with nuclear messenger RNA export [1].

1: Functional and structural characterization of the mammalian TREX-2 complex that links transcription with nuclear messenger RNA export. Jani D, Lutz S, Hurt E, Laskey RA, Stewart M, Wickramasinghe VO; Nucleic Acids Res. 2012;40:4562-4573. PMID:22307388