Class II MHC transcriptional mutants are defective in higher order complex formation.

摘要: Human class II MHC genes are regulated in part by a series of conserved upstream sequence elements termed the X1, X2, and Y boxes. Class transcriptional mutant B cell lines have been defined that differ with regard to presence RFX, an X1 box DNA-binding activity. To further characterize these lines, we tested ability respond known activation domains. A HLA-DRA promoter reporter constructions carrying Gal4 binding sites GAL4 fusion protein expression vectors were cotransfected into both wild type cells representing two RFX phenotypes. Regardless or phenotype, domains GAL4-VP16 GAL4-E1a could synergistically stimulate containing X2 GAL4-VP16- GAL4-E1a-mediated was inhibited contained RFX. In lacked not inhibited. RFX-positive line RJ2.2.5, inhibitory activity be overcome separating site from additional helical turns, suggesting factor is bound at sterically interferes activation. This case cells, stable higher order complex forms cells.