Mapping cis-acting defects in promoters of transcriptionally silent DQA2, DQB2, and DOB genes.

Defects in promoters of the nonexpressed DQA2, DQB2, and DOB genes from the class II major histo-compatibility complex were mapped by placing Z and X boxes of these silent genes into a synthetic DRA promoter. These conserved upstream sequences confer B-cell-specific and gamma-interferon-inducible expression to the DRA gene. Since DRA promoters containing the X box from the DQA2 gene and Z boxes from DQA2, DQB2, and DOB genes were neither expressed constitutively in B cells nor inducible by gamma interferon in fibroblastic cells, these conserved upstream sequences are implicated in the transcriptional defects of these silent genes.