To search your query sequence against a database of protein blocks you can
search The Blocks Database.
The blocks for the BLOCKS database are made automatically by looking for
the most highly conserved regions in groups of proteins represented in
the PROSITE database. These blocks are then calibrated against the SWISS-PROT
database to obtain a measure of the chance distribution of matches. It is
these calibrated blocks that make up the BLOCKS database.
http://www.blocks.fhcrc.org/
and then select "Block Searcher"