Annotation by sequence search.

Meaning are assigned to candidate genes mentioned above by comparing their sequences with the sequences of known functions available in the databases. This is based on the assumption that conserved sequences reflect common functional relationships. This is particularly true of house keeping genes like those meant for metabolism, gene regulation, defence, etc.

For instance, the functions of 69% of Arabidopsis genes were classified according to sequence similarity, although exact functions of all these genes could not be predicted. The sequences whose meanings still remain unknown will be studied following one of the several experimental approaches that are available, some of them making a part of proteomics research discussed later in this. Several bioinformatics tools (BLAST searches) that are available for annotation through sequence similarity are described and discussed.