Class Notes (807,159)
Canada (492,645)
Biology (2,220)
BIO230H1 (243)
Lecture 7

Lecture 7.docx

5 Pages
Unlock Document

University of Toronto St. George
Darrel Desveaux

Lecture 7: Examining Post-translational regulation **Notes only make sense when read alongside the lecture slides posted on Blackboard** BIO 230 October 1, 2013 Chris Garside scientists can examine the entire proteome of a cell. 2 dimensional gel electrophoresis fig 7-4 on slide each spot represents different proteins proteomes different in 2 tissues (brain and liver) a lot of this attributable to post transcriptional and post translational regulation since there is translational and post-translational regulation, RNA can be different but that doesn't necessarily mean that the protein will be different. because there are regulatory steps at so many levels. translational control very rapid. Prokaryotes: mRNAs have six nucleotide Shine-Dalgarno sequence AUG codon is where translation will initiate shine-Dalgarno required for efficient translation. it correctly positions AUG codon in the ribosome. much of translational control mechanisms revolve around having access to shine-Dalgarno sequence PROKARYOTES: MECHANISM TRANSLATIONAL REGULATION 1 RNA binding protein blocks access to SD sequence. translational repressor protein blocks access to SD sequence by binding to it how RNA molecules can adapt secondary structures. by interacting with different sequences found in RNA molecules. single stranded RNA molecules fold up in elaborate ways to form base pairing. RNA interacting with itself at the stem. stem is red and blue (on slide) PROKARYOTUIC MECHANISM TRANSLATIONAL REGULATION 2: listeria monocytogenes causes listeriosis. its proteins expressed under specific conditions: regulated by RNA structures that are temperature regulated. RNA molecules adapt a stem loop structure under 30C so that SD sequence is not accessible. but when temp above 30C stem loop melts and there is exposure of SD sequence, therefore virulence proteins expressed. pathogen only expressed when inside host. PROKARYOTUIC MECHANISM TRANSLATIONAL REGULATION 3: riboswitches when a small molecule binds to RNA, it can cause structural rearrangement of the RNA, blocking the SD sequence. SD no longer accessible when no small molecule bound, SD exposed and protein is expressed riboswitches either turn translation on or off depending on how it binds to RNA and alters its structure PROKARYOTUIC MECHANISM TRANSLATIONAL REGULATION 4: antisense RNA antisense RNA binds to RNA molecule and overlaps with SD. therefore, SD becomes inaccessible to ribosome. therefore, no translation. a base pairing interaction - so antisense RNA must be complimentary to RNA. antisense RNA coded in genome and then goes and binds to other RNAs, genome regulates its own translation TRANSLATIONAL REGULATION IN EUKARYOTES: no SD sequences that regulate translation but similar repressors that bind to start codon near AUG (initiator) and therefore interfere with translation initiation i.e.: cytosolic aconitase regulating expression of ferritin. ferritin not needed when iron low in cell; only needed when iron is high in body. cytosolic aconitase is an iron binding molecule. it undergoes a conformational change when it binds to iron. therefore, it can directly sense iron. repressor proteins can also interfere with 5' cap and 3' poly-A tail. these 2 things required for efficient translation. there are repressor proteins that interfere with translation factors interacting with cap and tail. there are small RNA molecules that can regulate eukaryotic translation. i.e.: Argonaut when there is not extensive RNA matching, RNA becomes p-bodies. therefore, translation of RNAs reduced. sequester RNA using micro-RNAs. a eukaryotic RNA regulatory mechanism. eIF2 forms a complex with GTP. eif2 bind to GTP and its attracting ribosome to initiator tRNA. small ribosomal subunit will start to
More Less

Related notes for BIO230H1

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.