Well curated, not just accumulated, by Amos Bairoch. A major problem with consensus sequences is the balance between specificity and precision in searching for matches. Elimination of false positives leads to making the search sequence very specific. This may make search fail to pick up known relatives of the motif, false negatives. High degree of ambiguity creates a problem that is difficult to surmount.
Consensus sequences are also discrete - match or no match.
Probability is missing in the analysis. All these considerations lead to development of probabilistic methods to generate possibly significant alignments of protein sequences Matrices and Profiles Common structure and function in a protein may lead to a limited similarity of amino acid sequence - conservative substitutions, redundancy in functional residues, etc. Still an active area of computational biology in refinements of search algorithms. Finding a homologue or protein with possible related function is a clue. Requires up to date database and powerful search engine.