Som1 is a component of the mitochondrial protein export system. The various Som1 proteins exhibit a highly conserved region and a pattern of cysteine residues [1]. Stabilisation of Som1 occurs through an interaction between Som1 and Imp1, a peptidase required for proteolytic processing of certain proteins during their transport across the mitochondrial membrane [2]. This suggests that Som1 represents a third subunit of the Imp1 peptidase complex [2]

1: The Saccharomyces cerevisiae SOM1 gene: heterologous complementation studies, homologues in other organisms, and association of the gene product with the inner mitochondrial membrane. Bauerfeind M, Esser K, Michaelis G; Mol Gen Genet. 1998;257:635-640. PMID:9604886

2: Som1, a third component of the yeast mitochondrial inner membrane peptidase complex that contains Imp1 and Imp2. Jan PS, Esser K, Pratje E, Michaelis G; Mol Gen Genet. 2000;263:483-491. PMID:10821182