Figure 1.

Modulatory region 1 (MR1) contains a highly conserved subregion containing known myogenic control element motifs. Sequence alignment of MR1 reveals a highly conserved 95-bp subregion, muscle creatine kinase (MCK) small intronic enhancer (MCK-SIE), that contains five putative control elements: an E-box motif pair, a myocyte enhancer factor 2 (MEF2) consensus motif and partially overlapping sequences that match proven MAF half-site and activator protein 1 (AP-1) sequences (see also Additional file 1 Figure S1). Bases that are identical in all six species (Homo sapiens, Felis catus, Bos taurus, Sus scrota, Canis familiaris and Mus musculus) are shown in black, while bases conserved between at least three species are shown in gray. The 3'-E-box is present in all six species, but is slightly more 5' in the mouse and further 5' in the dog. Conformation of mouse control element sequences to the MyoD/myogenin and MEF2 consensus sequences are indicated below the mouse sequence (+ = conforms, - = differs).