Conserved major histocompatibility complex class II boxes--X and Y--are transcriptional control elements and specifically bind nuclear proteins.

Abstract

A conserved sequence motif exists at the 5' end of all major histocompatibility complex class II genes. This motif consists of the 14-base X and Y boxes separated by a short stretch of variable sequence. In this report, we provide evidence that the X and Y boxes play an important role in controlling transcription of the murine class II gene El. We have developed transgenic mouse lines that carry Ea genes cleanly deleted for either the X or Y box and have compared the expression of these mutant transgenes with that of a nondeleted control. Both the X and the Y segments appear critical for accurate and efficient transcription of Ek. The most drastic effect is seen with y-interferon-treated macrophages, where deletion of the Y box completely abrogates transcription initiated by the normal promoter. In addition, we identify proteins from nuclear extracts that bind specifically to the X or Y box.

Identification and Characterization of Basal and Cyclic AMP Response Elements in the Promoter of the Rat Hexokinase II Gene

“…The synthetic oligonucleotides used as probes or competitors for EMSAs are listed in Table I. Oligonucleotides that contain the rat somatostatin CRE (40), a high affinity CCAAT/enhancer-binding protein (C/EBP) binding site (41), and the murine E␣ Y box (42) have been employed previously. Mutated sequences were identical to those employed in transfection experiments.…”

High mobility group I/Y protein functions as a specific cofactor for Oct-2A: mapping of interaction domains

“…The expression of human class II MHC genes, which is primarily controlled at the level of transcription [12,13], requires the accurate assembly of transcription factor complexes on a number of distinct conserved cis-elements located in their proximal promoter regions [14,15]. In addition to a TATA motif, these include the X, Y, and Z boxes; elements whose sequences as well as stereospecific relationships to each other are highly conserved [16][17][18][19][20][21][22][23][24][25][26]. Several proteins that interact specifically with these cis-acting elements have been described [27][28][29][30][31][32][33][34][35][36][37][38].…”

The Evolutionary History of CBF Transcription Factors: Gene Duplication of CCAAT – Binding Factors NF-Y in Plants

“…The CCAAT box is one of the most common upstream elements, found in approximately 25-30% of eukaryotic promoters (Bucher, 1990;Mantovani, 1998). It is typically located between 60-100 bp upstream of the transcription start site and it can function in direct or in inverted orientations (Dorn et al, 1987b;Bucher, 1990;Edwards et al, 1998;Mantovani, 1998;Stephenson et al, 2007) with possible cooperative interactions between multiple boxes (Tasanen et al, 1992) or other conserved motifs (Muro et al, 1992;Rieping and Schoffl, 1992;Edwards et al, 1998). CCAAT boxes are highly conserved within homologous genes across species in terms of position, orientation, and flanking nucleotides (Mantovani, 1998).…”