Table 2: All mer operon genes and their expressed proteins.

Gene	Gene Location in Operon	Protein Encoded	Protein Location	Function	References
merA	Immediately after transport genes	Mercuric reductase	Cytoplasm	Reduction of Hg+2 to Hg0	[8, 22].
merB	Immediately after transport genes	Organomercuriallyase	Cytoplasm	Lysis of C-Hg‏ bond	[8, 99].
merF	May be in plasmid between merP and merA	Transporter protein	Inner membrane	Narrow and broad spectrum system transporters of mercuric.	[90, 92].
merE	Downstream of merA and merB	Transporter protein	Inner protein	Uptake of inorganic and organo-mercurials (MeHg) into cytoplasm	[55, 89, 69].
merG	Between merA and merB	Organomercurial compounds resistance protein	Periplasm	Resistance to phenyl-mercury by efflux mechanism (reduce their cellular permeability)	[11, 89, 86]
merP	Upstream merA	Periplasmic Hg+2 binding protein	Periplasm	Transfer of Hg+2‏	[8, 11, 76].
merT	Upstream merA	Transporter protein	Inner membrane	Transporters of mercury in both narrow (Hg+2) and broad (phenyl mercury) spectrum systems.	[89, 90].
merD	Downstream merA	Regulator protein	Cytoplasm	Negatively regulates the mer operon	[109, 110,.
merC	Upstream merA	Transporter protein	Inner membrane	Narrow and broad spectrum system transporters of mercuric.	[90],
merR	Before transport genes	Regulator protein	Cytoplasm	Positively regulates the mer operon	[11, 22, 76, 89, 106].
merH	Immediately adjacent to merA	Mercury trafficking protein (metallochaperone)	Cytoplasm	Trafficking of mercury	[95, 161].
merI	Located 3’ to merA	Unknown		Have no role in mercury resistance or regulation	[95, 161].