Zinc finger X-linked duplicated family member C (ZXDC) is an 858 amino acid protein belonging to the ZDX family. Localized to the nucleus, ZDXC is expressed at high levels in heart, kidney, liver and testis, with lower levels of expression in lung, muscle, placenta, small intestine and spleen. ZDXC, with ZDXA, forms a complex that binds to the class II trans-activator (CIITA). CIITA, like the X1-binding regulatory factor X (RFX) complex and the nuclear factor Y (NFY) complex, is a transcriptional co-factor that is necessary, but not sufficient, for major histocompatibility complex (MHC) class II gene transcription. ZXDC, by regulating CIITA function, activates the transcription of MHC genes.