In budding yeast (Saccharomyces cerevisiae), SUI1 is a translation initiation factor that functions in concert with eIF-2 and the initiator tRNA-Met in directing the ribosome to the proper start site of translation [1]. SUI1 is a protein of 108 residues. Close homologs of SUI1 have been found [2] in mammals, insects and plants.

SUI1 is also evolutionary related to:

• Hypothetical proteins from bacteria such as Escherichia coli (yciH) or Haemophilus influenzae (HI1225).
• Hypothetical proteins from archaea such as Methanococcus jannaschii (MJ0463).

Two eukaryotic proteins also seem to contain a C-terminal SUI1-like domain. These are:

• Density-regulated protein (gene: DENR). This protein is found in mammals, insects, nematodes, plants and fungi.
• Ligatin (gene: LGTN). This protein is found in mammals and insects.

The profile we developed covers the entire C-terminal SUI1-like domain.