A gene in the archaebacterium Sulfolobus solfataricus that codes for a protein equivalent to the alpha subunits of the signal recognition particle receptor in eukaryotes

Summary We have sequenced a gene in the archaebacterium Sulfolobus solfataricus that codes for a protein that shows sequence similarity to the alpha subunit of the signal recognition particle receptor or docking protein In eukaryotes and the product of the ftsY gene in Escherichia coli. Comparison of the Sulfolobus‘docking protein’ with its eukaryotic and eubacterial counterparts showed that the region of highest sequence similarity corresponds to a GTP-binding site. The presence of this gene in archaebacteria suggests that some of the components involved in protein transport have been conserved in the three kingdoms.