FIG. 2.

Configurations, gene names, and protein names for the six rhodopsins and their cognate transducers from H. marismortui. HmBRI (bop) is a light-driven proton transporter; HmHR (hop) is a light-driven chloride transporter; HmBRII (xop1), originally predicted to be a BR precursor, is, like HmBRI, a light-driven proton transporter; and HmSRM (xop2), which was annotated as an “opsin of unknown function,” associates with HmHtrM (htrM), and its function is yet to be determined. HmSRI (sop1) associates with reHmHtrI (htr1), and HmSRII (sop2) associates with HmHtrII (htr2) to mediate photoattractant and photorepellent responses, respectively. The blue box indicates the two rhodopsins that are in addition to the currently known four-rhodopsin system identified from H. salinarum.