BIOL 200 Lecture Notes - Lecture 18: Histone Acetyltransferase, Heterochromatin Protein 1, Bromodomain
7 Jun 2016
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Positive feedback loops give histone codes stability and tendency to spread along chromosome: tendency to spread along chromosome, ex. In addition to self-oligomerization, hp1 (and other chromodomain proteins) binds and recruits h3k9 methyl transferase. Heterochromatin, once initiated, tends to spread along chromosomes. Euchromatin also tends to spread along the chromosome because of a positive feedback loop (same reason as above^^: histones acetylation is code for euchromatin, acetylated histone tails bind bromodomain proteins. Start with 1 dna molecule and 4 nucleosomes. End with 2 dna molecules and 8 nucleosomes. Reason that we have 8 nucleosomes is because cell is also making histones. 4 nucleosomes are new from synthesis in cell cycle histones not modified, just came off the ribosomes, no methyl or acetyl groups. New ones and old ones are randomly partitioned between 2 dna daughter molecules. Hp1 binds to methyl group and recruits h3k9 methyl transferase and it methylates the adjacent nucleosomes.
