Boxes/HMGs

"Upstream Binding Factor (UBF) is important for activation of ribosomal RNA transcription and belongs to a family of proteins containing nucleic acid binding domains, termed HMG-boxes, with similarity to High Mobility Group (HMG) chromosomal proteins."

Chromosomal proteins
"Most HMG box proteins contain two or more HMG boxes and appear to bind DNA in a relatively sequence-aspecific manner (5, 13, 15, 16 and references therein). [...] they all appear to bind to the minor groove of the A/T A/T C A A A G-motif (10, 14, 18-20)."

"Previous studies in lymphocytes have described two DNA-binding HMG box proteins, TCF-1 and LEF-1, with affinity for the A/TA/TCAAAG motif found in several T cell-specific enhancers."

"The high mobility group-1 (HMG) box was originaly identified by Tjian and co-workers in the transcription factor UBF as a region of homology to HMG-1 proteins (Jantzen et al., 1990). UBF reportedly contained four such regions of -80 amino acids; one of these boxes was shown to mediate DNA binding."

"Interestingly, the sequence-specific HMG boxes characterized to date display high afinity to the A/TA/TCAAAG motif despite a low level of amino acid homology (typically <25% identity)."

"Human LEF-1 was originally identified as a T cell-specific protein binding to the TTCAAAG motif in the TCR-α enhancer (Waterman et al., 1991)."

"As analysed by gel retardation, the Sox-4 HMG box indeed bound to the AACAAAG motif (probe MWε-1; Figure 2B, lane 1). As described for other HMG boxes, Sox-4 interacted with DNA bases within the minor groove: substitution of A/T pairs for I/C pairs, which leaves the surface of the minor groove intact (Star and Hawley, 1991), had no apparent effect on binding affinity (lanes 2 and 4)."

Consensus sequences
"In mammals, the Tcf/Lef family consists of four genes: Tcf‐1, Lef‐1, Tcf‐3 and Tcf‐4. All TCF/LEF proteins display several common structural features (48,49). They contain a nearly identical DNA‐binding domain, the HMG box, recognizing the consensus sequence A/T A/T CAAA."