Gal3-Gal80-Gal4 proteins of yeast comprise a signal transducer that controls the galactose-inducible Gal4-mediated transcription activation of GAL regulon genes. In the absence of galactose Gal80 binds to Gal4 and prohibits it from activating transcription. In the presence of galactose, Gal3 binds to Gal80 to prohibit its inhibition of Gal4. For Gal4 details see User:Amir Mitchell/Gal4.
The Gal4 protein consists of a of identical subunits.
3D Structures of Gal3-Gal80-Gal4
Updated on 18-August-2014
3v5r – yGal3 – yeast
3v2u – yGal3 + Gal80 + ATP + galactose
1aw6 – yGal4 DNA-binding domain – yeast – NMR
1hbw - yGal4 dimerization domain – NMR
3coq - yGal4 DNA-binding and dimerization domains + DNA
1d66 – yGal4 + DNA
2nvw – KlGal80 – Kluyveromyces lactis
3e1k – KlGal80 + lactose regulatory protein Lac9 peptide
3btu, 3btv – yGal80 (mutant)
3bts – yGal80 + Gal4 peptide + NAD