Assuming the sequence shown is read left to right, what is the sequence of the protein produced?


MY ATTEMPT: I know RNA is synthesized 5 to 3. This is throwing me off because if we read the above sequence from left to right then we are going to synthesize 3 to 5. If I ignore this for now, I get an mRNA of 3'-UACAUGAAGGUAGACCUUAUC-5' from this i could easily get the protein looking at a mRNA to protein chart. Is this correct?

  • $\begingroup$ You might be interested in the exPASy translation tool (and loads of other goodies at this site) $\endgroup$ – user1136 Oct 3 '12 at 20:05

Since the sequence starts with an initiation codon and ends with a stop codon I think it's safe to conclude that this is the coding strand. The coding strand has the same sequence as the transcribed RNA (except T>U). This is because it is the other strand of the DNA that is the template for the synthesis of an RNA. The RNA is indeed made 5'>3', but the template it uses has to run in the opposite direction.

3'-TACATGAAGGTAGACCTTATC-5' template strand

3'-TACATGAAGGTAGACCTTATC-5' template strand (read from left to right by the polymerase)

and the sequence of the protein is MetTyr...etc

  • $\begingroup$ but this way the sequence i gave is not being read from left to right. you read the complement from left to right $\endgroup$ – Kirby Oct 4 '12 at 1:42
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    $\begingroup$ Depends what you mean by "read". The polymerase moves from left to right reading the bottom strand as template and making the RNA from left to right. You read the top strand from left to right as you look up codons in a genetic code table. You use the top strand for this because it is this DNA strand that has the same sequence as the mRNA. $\endgroup$ – Alan Boyd Oct 4 '12 at 5:16

EMBOSS has a tool for doing this: http://www.ebi.ac.uk/Tools/st/emboss_transeq/


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