MALSU1
MALSU1 is a gene on chromosome 7 in humans that encodes the protein MALSU1. This protein localizes to mitochondria and is probably involved in mitochondrial translation or the biogenesis of the large subunit of the mitochondrial ribosome.
Protein
MALSU1 is a member of the DUF143 family which is highly conserved in both prokaryotes and eukaryotes but not archaea. Examples of mammalian conservation are given below using the ALIGN tool from the San Diego Supercomputer Center Biology Workbench. Percentages indicate the identity shared by the human protein and the respective mammalian protein. Accession numbers are from the NCBI database.| Species | Accession # | Identity |
| Macaca mulatta | XP_001098609 | 93.20% |
| Sus scrofa | NP_001092054 | 85.50% |
| Bos taurus | NP_001068866 | 88.50% |
| Canis familiaris | XP_853850 | 77.30% |
| Rattus norvegicus | NP_001100063 | 81.60% |
| Equus caballus | XP_001497879 | 90.70% |
There are no known or predicted paralogs in Homo sapiens. That is, MALSU1 is a single-copy gene.
The domain is from position 93 to 194 on the human protein and comprises 43.2% of the sequence. This conserved domain is also present in the plant gene iojap, a pattern-striping gene in maize. However, since its function has been solved at least in bacteria, it is no longer a "domain of unknown function".
Protein function
While the function of the protein in mitochondria is not conclusive its bacterial homolog has been shown to silence bacterial translation by blocking the two ribosomal subunits from joining, hence it was called RsfS.Protein-protein interactions. RsfS has been shown via a yeast two-hybrid screen to interact with ribosomal protein L14 in four bacterial species as well as in mitochondria. MALSU1 was shown to interact with CHMP protein which is part of the ESCRT-III complex. DUF143 has also been shown to interact with UFD1, tRNA synthetases class II, and Cytidylyltransferase in various architectures.