BIO230H1 Lecture Notes - Lecture 7: Guanine Nucleotide Exchange Factor, Antisense Rna, Eif2
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BIO230H1 Full Course Notes
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Both prokaryotes and eukaryotes use translational control mechanisms to regulate protein expression often in response to stressful situations such as low nutrients, infection or environmental stresses (e. g. , temperature). Mechanism 1: rna binding protein blocks access to sd sequence: no protein is made, no translation as rna is not correctly positioned. Mechanism 3: riboswitch: e. g. , s-adenosyl methionine, a small molecule causes structural rearrangement of rna, blocks the sd sequence, no protein is made. Mechanism 4: antisense rna: e. g. , iron storage proteins, an antisense rna is produced elsewhere in the genome, antisense rna base-pairs with mrna and blocks sd, note: this is different from microrna in eukaryotes. Repressor proteins can interfere with 5" cap and 3" poly-a tail interactions that are required for efficient translation. Small rna molecules can also regulate eukaryotic translation (mirnas) but different mechanism than in prokaryotes. Also other eukaryotic specific mechanisms (e. g. , eukaryote initiation factor, or eif2) Eukaryotic specific translational regulation: regulation of eukaryotic initiation factors (eifs)