not for a string in regular expressions

How do I search a sequence for a certain match not containing a certain substring?

As in wanting to search an RNA sequence starting with CG and not containing AG in the middle and then ending with it? When I run

regexp(mRNA, 'GU\w+[^AG]AG');

it gives me the location of matches that dont contain either A or G in the middle, and not the 'AG' substring.

Would really appreciate the help!

Answer 1

[Walter Roberson]

Presuming that mRNA is a cell array of character vectors, then

mask = ~cellfun(@isempty, regexp(mRNA, '^CG([^A]|A[^G])*AG$', 'lineanchors', 'once'));
matched_strings = mRNA(mask);