# Conserved sequence

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In biology, conserved sequences are similar or identical sequences that may occur within nucleic acids, proteins or polymeric carbohydrates within multiple species of organism or within different molecules produced by the same organism. In the case of cross species conservation, this indicates that a particular sequence may have been maintained by evolution despite speciation. The further back up the phylogenetic tree a particular conserved sequence may occur the more highly conserved it is said to be.

## Conserved nucleic acid sequences

The TATA promoter sequence is an example of a highly conserved DNA sequence, being found in most eukaryotes.

## Conserved protein sequences

Shown below is an amino acid sequence alignment between two human zinc finger proteins, with GenBank accession numbers AAB24882 and AAB24881. Alignment was carried out using the clustalw sequence alignment program. Conserved amino acid sequences are marked by strings of ${\displaystyle \mathrm {*} }$ on the third line of the sequence alignment. As can be seen from this alignment, these two proteins contain a number of conserved amino acid sequences.

## Conserved polymeric carbohydrate sequences

The monosaccharide sequence of the glycosaminoglycan heparin is conserved across a wide range of species.

## Biological role of sequence conservation

Sequence similarities serve as evidence for structural and functional conservation, as well as of evolutionary relationships between the sequences. Consequently, comparative analysis is the primary means by which functional elements are identified.

Among the most highly conserved sequences are the active sites of enzymes and the binding sites of a protein receptors.

## References

• Thompson JD, Gibson TJ, Plewniak F, Jeanmougin F, Higgins DG (1997). The ClustalX windows interface: flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Research, 25:4876-4882.