Of the 1,528 annotated CDSs, a function was assigned to 989 CDSs (64.7%). For 784 of them (79.3%), a function was experimentally demonstrated either in the Helicobacter species (188, 12.3%) or in another organism (596, 39%). Two hundred and five CDSs (20.7% of 989) received a function based on the presence of a conserved amino acid motif, a structural feature, or limited homology. A total of 378 CDSs have homologs in previously reported sequences of the genus Helicobacter (43.6% of 378), in the epsilon proteobacteria (35.2% of 378), or in other distant bacteria (21.2% of 378). Protein function classification based on the cluster orthologous genes classification (COG) database allowed us to place 1189 of the 1528 CDSs (77.81%) in at least one of the COG functional groups (Table 2): 454 were assigned to cellular processes and signaling systems, 342 to information storage and processing, while 595 were involved in metabolism. The B38 genome exhibits the highest percentage of CDSs associated with a COG group (77.97% vs 73.38% for 26695, 76.48% for J99, 76.15% for HPAG1 and, 73.49 for Shi470), with the number of CDSs involved in defense mechanisms slightly higher than in the other sequenced Helicobacter strains.