In both prokaryotes and mitochondria they are localized to the outer membrane, and have been shown to bind and transport dicarboxylic tetrapyrrole intermediates of the haem biosynthetic pathway.
They are localized to the outer membrane. This is in both prokaryotes. This is in mitochondria. They have been shown to bind and transport dicarboxylic tetrapyrrole intermediates of the haem biosynthetic pathway. This was in both prokaryotes. This was in mitochondria.