The REPRO server: finding protein internal sequence repeats through the Web.

European Molecular Biology Laboratory in Heidelberg, Germany, in 1992, the late Sir Karl Popper remarked that ‘science is like a black man searching a black room for a black cat that might not be there’. A researcher having a protein sequence at hand and wishing to find internal sequence repeats is faced with exactly this problem. Worse still, he or she might not even know what a cat is. If some help is available in that a motif is known, or there is a notion of amino acid conservation (i.e. the cat is known), then a myriad of software is available to use this information and delineate the reincarnations of the motif or pattern (for a list of available software, see http://www. expasy.ch/tools/#pattern). However, if no such patterns are available, the problem of recognizing and delineating repeats becomes distinctly more difficult (for a review, see Ref. 1). With the availability of complete genome sequences, it is becoming clear that sequence repeats are ubiquitous TIBS 25 – OCTOBER 2000