Introduction to Sequence Analysis

The basis of all sequence comparison is predicated on evolutionary relationships, or homology. The more similar are two protein (or nucleic acid) sequences then the greater the probability that they are descended from a common ancestor, and hence more likely to have a similar function. One of the first steps in the characterization of a 'new' protein is searching existing databases to find other proteins that are sufficiently similar so that functional and structural characteristics may be inferred. An understanding of the ways in which such comparisons are performed may help the scientist be more effective in performing such searches and interpreting the results.