mRNA Splicing

#shorts I  splicing I Prof. Dr. Jariya I gene_expression I transcription I post_transcriptional_modifications
Coordinated expression of galactose circuit is mediated by the protein Gal4 where Gal stands for galactose. Gal4 is an STF it binds to a short regulatory DNA sequence upstream of each of the genes, the sequence is called ‘upstream activating sequence Gal (UAS Gal) . Binding of Gal4 to UASGal  through zinc fingers in its DBD occurs both in the absence and presence of galactose. When sugar is absent the regulatory protein Gal80 binds Gal4 at its TAD and covers or hides its transcription activation domain so that it cannot recruit proteins required for transcription of genes for metabolism of galactose. In contrast to this when galactose is present in environment of yeast, it activates another player the Gal3 protein, Gal3 allures and binds Gal80, Gal 80 binding to Gal3 uncovers the Transcription activation domain of Gal 4. So Gal 4 is able to recruit transcription factors required for transcription of genes for galactose metabolism. So these genes are transcribed into mRNA necessary for synthesis of enzymes which metabolize galactose. In contrast to this when galactose is present in environment of yeast, it activates another player the Gal3 protein, Gal3 allures and binds Gal80, Gal 80 binding to Gal3 uncovers the Transcription activation domain of Gal 4. So Gal 4 is able to recruit transcription factors required for transcription of genes for galactose metabolism. So these genes are transcribed into mRNA necessary for synthesis of enzymes which metabolize galactose
Glucose prevents the use of galactose by inhibiting the expression of Gal4 protein.