Palindromic sequence
As a palindromic sequence in which is genetics a (short) base sequence of DNA or RNA refers to the opposite direction in complementary base pairing results in the same base sequence.
Since the opposing strands in a double strand of nucleic acids are oriented in opposite directions ( antiparallel ), palindromic sequences of single strands can complementary pairs with others of the same nucleotide sequence and form double-stranded areas, for example to form the stem of a hairpin structure (see picture), in DNA as in RNA .
Such nucleotide sequences are similar to one another and each represent character strings which indicate the reverse complement when the reading direction is reversed. They are thus similar to an expression that is read from the front as well as from the back and are therefore called palindromic .
For example, the following sequence of bases is a palindromic sequence:
- 5'-GAATTC-3 '
- 3'-CTTAAG-5 '
Most of the DNA-binding and modifying proteins recognize short palindromic sequences and carry out their activities symmetrically on both strands. The example shown above is the recognition sequence for a known restriction enzyme , EcoRI . EcoRI recognizes this sequence within a DNA double strand and cuts both DNA strands between the nucleobases G (uanin) and A (denin). The shortest sequence palindrome with an important function is the CpG nucleotide , important in the epigenetic DNA methylation of CpG islands .
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- Wilfried Janning, Elisabeth Knust: Genetics: general genetics, molecular genetics, developmental genetics. P. 269f. Georg Thieme Verlag, 2004. ISBN 9783131287717