These proteins contain a conserved basicDNA binding domain that binds theE box DNA motif.[2] They dimerize with otherHLH containing proteins through an HLH-HLH interaction.[3]
There are typically four vertebrate MRFparalogues which are homologous to typically a single MRF gene innon-vertebrates. These four genes are thought to have been duplicated in thetwo rounds of whole-genome duplication early invertebrate evolution that played a role in the evolution of more complex vertebrate body plans. The four MRFs have four distinctexpression profiles, though with some redundancy, asMyoD andMyf5 are both involved in myoblast determination, and are followed by the activation ofMyf6 (MRF4) andMyog in myoblast differentiation.[4] There have also been instances of independent duplication of the MRFs in invertebrate lineages, similarly followed bysubfunctionalization of the expression of the genes in time and/or in space. Inamphioxus, an invertebrate chordate closely related to vertebrates, there are five MRFs which are expressed in different patterns during development.[5]
^Weintraub H, Davis R, Tapscott S, Thayer M, Krause M, Benezra R, Blackwell T, Turner D, Rupp R, Hollenberg S (1991). "The myoD gene family: nodal point during specification of the muscle cell lineage".Science.251 (4995):761–6.Bibcode:1991Sci...251..761W.doi:10.1126/science.1846704.PMID1846704.
^Barndt R, Zhuang Y (1999). "Controlling lymphopoiesis with a combinatorial E-protein code".Cold Spring Harb Symp Quant Biol.64:45–50.doi:10.1101/sqb.1999.64.45.PMID11232321.
