Myogenic regulatory factors (MRF) are
basic helix-loop-helix (bHLH)
transcription factor
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription (genetics), transcription of genetics, genetic information from DNA to messenger RNA, by binding t ...
s that regulate
myogenesis
Myogenesis is the formation of skeletal muscle, skeletal muscular tissue, particularly during embryonic development.
Skeletal muscle#Skeletal muscle cells, Muscle fibers generally form through the fusion of precursor cell, precursor myoblasts in ...
:
MyoD
MyoD, also known as myoblast determination protein 1, is a protein in animals that plays a major role in regulating muscle differentiation. MyoD, which was discovered in the laboratory of Harold M. Weintraub, belongs to a family of proteins kn ...
,
Myf5,
myogenin
Myogenin, is a transcriptional activator encoded by the ''MYOG'' gene.
Myogenin is a muscle-specific basic-helix-loop-helix (bHLH) transcription factor involved in the coordination of skeletal muscle development or myogenesis and repair. Myogeni ...
, and
MRF4.
These proteins contain a conserved basic
DNA binding domain that binds the
E box DNA motif. They dimerize with other
HLH containing proteins through an HLH-HLH interaction.
MRF Gene Family Evolution
There are typically four vertebrate MRF
paralogues which are homologous to typically a single MRF gene in
non-vertebrates. These four genes are thought to have been duplicated in the
two rounds of whole-genome duplication early in
vertebrate
Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain.
The vertebrates make up the subphylum Vertebra ...
evolution that played a role in the evolution of more complex vertebrate body plans. The four MRFs have four distinct
expression profiles, though with some redundancy, as
MyoD
MyoD, also known as myoblast determination protein 1, is a protein in animals that plays a major role in regulating muscle differentiation. MyoD, which was discovered in the laboratory of Harold M. Weintraub, belongs to a family of proteins kn ...
and
Myf5 are both involved in myoblast determination, and are followed by the activation of
Myf6 (MRF4) and
Myog in myoblast differentiation. There have also been instances of independent duplication of the MRFs in invertebrate lineages, similarly followed by
subfunctionalization of the expression of the genes in time and/or in space. In
amphioxus, an invertebrate chordate closely related to vertebrates, there are five MRFs which are expressed in different patterns during development.
References
External links
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{{Transcription factors, g1
Transcription factors
DNA-binding proteins