The most highly conserved regions of proteins can be represented as blocks
of aligned sequence segments, typically with multiple blocks for a given pr
otein family, The Blocks Database World Wide Web (http://blocks;fhcrc.org)
and e-mail (blocks @ blocks. fhcrc.org) servers provide tools to search DNA
and protein queries against the Blocks+ Database of multiple alignments. W
e describe features for detection of distant relationships using blocks. Bl
ocks+ includes protein families from the PROSITE, Prints, Pfam-A, ProDom an
d Demo databases. Other features include searching Blocks+ with the BLIMPS
and NCBl's IMPALA programs, sequence logos, phylogenetic trees, three-dimen
sional display of blocks on PDB structures, and a polymerase chain reaction
(PCR) primer design strategy based on blocks.