Nuclear Transcription Factor, X-Box Binding Protein 1 (NFX1)

MHC class II gene expression is controlled primarily at the transcriptional level by transcription factors that bind to the X and Y boxes, two highly conserved elements in the proximal promoter of MHC class II genes. Transcriptional repressor NF-X1 is a transcriptional repressor capable of binding to the conserved X box motif of HLA-DRA and other MHC class II genes in vitro. The protein may play a role in regulating the duration of an inflammatory response by limiting the period in which class II MHC molecules are induced by IFN-γ. Three alternative splice variants, each of which encodes a different isoform, have been identified. The predicted 1,104-amino acid protein has a central cysteine-rich DNA-binding domain that is subdivided into 7 repeated motifs; the motif is similar to, but distinct from, LIM and RING finger domains.