Myoblast Myogenic Differentiation but Not Fusion Process Is Inhibited via MyoD Tetraplex Interaction

Figure 1

Multiregion view of the Myog, Mymk, Myod1, and MHC genomic regions. (A) Coding exons are represented by blocks connected by horizontal lines representing introns. The 5 and 3 untranslated regions (UTRs) are displayed as thinner blocks on the leading and trailing ends of the aligning regions. Arrowheads on the connecting intron lines indicate the direction of transcription. Mymk has multiple representations because two alternative splicings are known (NM_001159602 and NM_025376). (B) Sequence conservation of the considered region in mammals: CDS are the higher conserved regions, because of the pressure toward the maintenance of the codified peptides. Also, the UTR regions are largely conserved, supposedly for functional constraints. (C) Putative tetraplex sites, bioinformatically predicted on the forward or reverse strands (G3L1–7 and C3L1–7 labels, resp.): those in black have highly conserved sequence in mammals, that is, signal of both a conservative pressure against the divergence that leads to speciation and a function shared among all mammals. (D) CpG island site. False-positive prediction of tetraplex sites may be due to high concentration of G in these islands, but this is not the case of the four considered genes. (E) Repeats. Also, repeats with high percentage in GC may lead to false-positive tetraplex prediction, but this is not the case for the three conserved tetraplexes (black boxes in (C)). (F) Putative transcription factor-binding sites. The presence of both a tetraplex and a transcription factor-binding site in close proximity, as well as in the same sequence, strongly suggests that the two sites may collaborate to modulate the transcription factor effect on the genes.