Determination of reliable regions in protein sequence alignments

Judging the significance of alignments is still a major problem in sequence comparison. We present a method to delineate reliable regions within an alignment. This differs from standard approaches in that it does not attempt to attribute one significance value to the alignment as a whole, but assesses alignment quality locally. An algorithm is provided that predicts which residue pairs in an alignment are likely to be correctly matched. The predictions are evaluated by comparison with alignments taken from tertiary structural superpositions.