 Genes in E. coli are usually named by 4 @-@ letter acronyms that derive from their function ( when known ) . For instance , recA is named after its role in homologous recombination plus the letter A. Functionally related genes are named recB , recC , recD etc . The proteins are named by uppercase acronyms , e.g. RecA , RecB , etc . When the genome of E. coli was sequenced , all genes were numbered ( more or less ) in their order on the genome and abbreviated by b numbers , such as b2819 ( = recD ) etc . The " b " names were created after Fred Blattner who led the genome sequence effort . Another numbering system was introduced with the sequence of another E. coli strain , W3110 , which was sequenced in Japan and hence uses numbers starting by JW ... ( Japanese W3110 ) , e.g. JW2787 ( 
