The fork head domain is a type of
protein domain
In molecular biology, a protein domain is a region of a protein's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist of ...
that is often found in
transcription factor
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The f ...
s and whose purpose is to bind
DNA.
Function
The fork head protein of ''
Drosophila melanogaster
''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the " vinegar fly" or "pomace fly". Starting with ...
'', a transcription factor that promotes terminal rather than segmental development, contains neither
homeodomain
A homeobox is a DNA sequence, around 180 base pairs long, that regulates large-scale anatomical features in the early stages of embryonic development. For instance, mutations in a homeobox may change large-scale anatomical features of the full ...
s nor
zinc-finger
A zinc finger is a small protein structural motif that is characterized by the coordination of one or more zinc ions (Zn2+) in order to stabilize the fold. It was originally coined to describe the finger-like appearance of a hypothesized struc ...
s characteristic of other transcription factors.
Instead, it contains a distinct type of
DNA-binding region, containing around 100 amino acids, which has since been identified in a number of transcription factors (including ''D. melanogaster'' FD1-5, mammalian
HNF3, human
HTLF, ''
Saccharomyces cerevisiae
''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungus microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have b ...
'' HCM1, etc.). This is referred to as the fork head domain but is also known as a "
winged helix".
The fork head domain binds
B-DNA as a monomer,
but shows no similarity to previously identified DNA-binding
motifs. Although the domain is found in several different transcription factors, a common function is their involvement in early developmental decisions of cell fates during
embryogenesis
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
.
Members of the class O of forkhead box transcription factors (FoxO) have important roles in metabolism, cellular proliferation, stress tolerance and probably lifespan.
See also
*
FOX proteins
FOX (forkhead box) proteins are a family of transcription factors that play important roles in regulating the expression of genes involved in cell growth, proliferation, differentiation, and longevity. Many FOX proteins are important to embryonic ...
References
{{InterPro content, IPR001766
Protein domains
de:Forkhead-Box