Mitochondrial ribosomes synthesize core subunits of the inner membrane respiratory chain complexes. In mitochondria, ribosomes are mainly membrane associated and translation is tightly coupled to the inner mitochondrial membrane. Mdm38/Letm1 is a conserved membrane receptor for mitochondrial ribosomes and specifically involved in respiratory chain biogenesis.

The Letm1 ribosome-binding domain (RBD) is necessary and sufficient for interaction with mitochondrial ribosomes. It exhibits a predominantly α-helical compact fold (see <PDB:3SKQ>) and contains extended, highly charged surface patches. The conserved regions most probably represent interaction sites for ribosomal RNA or protein subunits, or for proteins involved in mitochondrial protein biogenesis [1,2].

The profile we developed covers the entire Letm1 RBD domain.