DNA sequence puzzle!

Paul N Hengen pnh at fcs260c2.ncifcrf.gov
Wed Mar 22 17:37:22 EST 1995


Alan Escher (aEscher at ccmail.llu.edu) wrote:

| .......the published coding strand is 5'...TCTAGA....ATG..3' and instead he
| obtained 5'..AGATCT...TAC....3'! This phenomenon has happened with another gene
| in another vector as well. Are we missing something obvious that is going to
| make me feel really stupid? No matter what kind of mistake was made in cloning,
| choice of oligo etc, we just should not get the noncoding strand changed from a
| 3' to 5' direction into a 5' to 3' orientation. Suggestions?

Ummmmmm. This may be a stupid answer, but are you sure the student read the
X-ray film the right way around? Maybe with all the maneuvers in gel handling
the film was upside down. If you had loaded the sequence as GATC and read it
backwards, it would give you CTAG. It might be a good idea to load the gel
asymetrically so you can't help but notice the pattern is backwards. This could
explain why it has happened more than once :-)

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