COGcollator: a web server for analysis of distant relationships between homologous protein families.

Background: The Clusters of Orthologous Groups (COGs) of proteins systematize evolutionary related proteins into specific groups with similar functions. However, the available databases do not provide means to assess the extent of similarity between the COGs.

Aim: We intended to provide a method for identification and visualization of evolutionary relationships between the COGs, as well as a respective web server.

COGNAT: a web server for comparative analysis of genomic neighborhoods.

Background: In prokaryotic genomes, functionally coupled genes can be organized in conserved gene clusters enabling their coordinated regulation. Such clusters could contain one or several operons, which are groups of co-transcribed genes. Those genes that evolved from a common ancestral gene by speciation (i.