FIG. 4.

Residues on the hydrophilic face of helix III differentiate MyoD and myogenin function. (A) The MyoDΔ245-258–myogenin 195-208 chimera was subjected to back mutagenesis, represented in this schematic. MyoD residues are underlined. Back mutants are identified by the sequence of the first five amino acids of helix III, i.e., VSSLD represents substitution of MyoD amino acids 245 to 249 into the chimeric protein. (B) S1 nuclease protection analysis of back mutations in the chimeric MyoDΔ245-258–myogenin 195-208 protein. ∗, partially digested probe.