This family includes ABC1 from yeast [1] and AarF from E. coli [2]. These proteins have a nuclear or mitochondrial subcellular location in eukaryotes. The exact molecular functions of these proteins is not clear, however yeast ABC1 suppresses a cytochrome b mRNA translation defect and is essential for the electron transfer in the bc 1 complex [1] and E. coli AarF is required for ubiquinone production [2]. It has been suggested that members of the ABC1 family are novel chaperonins [1]. These proteins are unrelated to the ABC transporter proteins.

1: ABC1, a novel yeast nuclear gene has a dual function in mitochondria: it suppresses a cytochrome b mRNA translation defect and is essential for the electron transfer in the bc 1 complex. Bousquet I, Dujardin G, Slonimski PP; EMBO J 1991;10:2023-2031. PMID:1648478

2: Identification and characterization of aarF, a locus required for production of ubiquinone in Providencia stuartii and Escherichia coli and for expression of 2'-N-acetyltransferase in P. stuartii. Macinga DR, Cook GM, Poole RK, Rather PN; J Bacteriol 1998;180:128-135. PMID:9422602