Mba1 is an inner membrane protein that is part of the mitochondrial protein export machinery [1][2]. It binds to the large subunit of mitochondrial ribosomes and cooperates with the C-terminal ribosome-binding domain of Oxa1, which is a central component of the insertion machinery of the inner membrane. In the absence of both Mba1 and the C-terminus of Oxa1, mitochondrial translation products fail to be properly inserted into the inner membrane and serve as substrates of the matrix chaperone Hsp70 [3]. It is proposed that Mba1 functions as a ribosome receptor that cooperates with Oxa1 in the positioning of the ribosome exit site to the insertion machinery of the inner membrane [3].

1: MBA1 encodes a mitochondrial membrane-associated protein required for biogenesis of the respiratory chain. Rep M, Grivell LA; FEBS Lett 1996;388:185-188. PMID:8690083

2: Mba1, a novel component of the mitochondrial protein export machinery of the yeast Saccharomyces cerevisiae. Preuss M, Leonhard K, Hell K, Stuart RA, Neupert W, Herrmann JM; J Cell Biol 2001;153:1085-1096. PMID:11381092

3: Mba1, a membrane-associated ribosome receptor in mitochondria. Ott M, Prestele M, Bauerschmitt H, Funes S, Bonnefoy N, Herrmann JM; EMBO J. 2006;25:1603-1610. PMID:16601683