BIOL 300 Lecture Notes - Lecture 6: Gcn4, Taf1, Arginine

• School: McGill University
• Department: Biology
• Course: BIOL 300
• Professor: Frieder Schoeck

Document Summary

Lecture 6 mechanism of transcriptional regulation by co-activators. How do transcription actor activation domains enhance transcription: they bind other proteins (co-activators) that, modify chromatin structure, promote formation of pre-initiation complex. Effects of histone tail modifications: reduction of the positively charge on these tails by acetylation or phosphorylation may reduce their interaction with negatively charged dna and decrease chromatin compaction. Crosslinking experiments showed interaction between histone tails and linker dna: specific modifications may serve as new binding sites for proteins which can alter chromatin structure and function (ex: the modifications create a histone code read by interacting proteins) Specific modifications are associated with open/closed chromatin states: heterochromatin (inactive/condensed, looking at h3, there is a methylation that is associated with h3k9 and. H3k27 (they are trimethylated in heterochromatin regions: euchromatin (active/open, the histone tails are often acetylated and phosphorylated, also specific methylation on h3k4 that is associated with actively transcribed genes (normally methylation is associated with transcription repression)