The following uncharacterized proteins have been shown [1] to share regions of similarities:

• Anabaena and related cyanobacteria protein hesB which may be required for nitrogen fixation.
• Escherichia coli hypothetical protein yadR and HI1723, the corresponding Haemophilus influenzae protein.
• Escherichia coli hypothetical protein ydiC.
• Escherichia coli hypothetical protein yfhF and HI0376, the corresponding Haemophilus influenzae protein.
• Mycobacterium tuberculosis hypothetical protein Rv2204c.
• Synechocystis strain PCC 6803 hypothetical protein slr1417.
• Synechocystis strain PCC 6803 hypothetical protein slr1565.
• A hypothetical protein in the nifU 5'region of many nitrogen fixing bacteria.
• Porphyra purpurea chloroplast hypothetical protein in apcF-rps4 intergenic region.
• Yeast hypothetical protein YLL027W.
• Yeast hypothetical protein YPR067W.

These are small proteins (106 to 135 amino-acid residues in bacteria, about 200 residues in fungi) that contain a number of conserved regions. The most noteworthy of these regions is located in the C-terminal extremity, it contains two conserved cysteines. We have used this region as a signature pattern.