The membrane proteins of the plant preprotein and amino acid transporter (PRAT) superfamily all share common structural elements, such as four membrane-spanning α-helices. Interestingly they display diverse localisation to outer and inner membranes of chloroplasts and mitochondria. Furthermore, they fulfil different functions in preprotein translocation as well as amino acid transport across these membranes. This review summarises current knowledge on precursor protein import and amino acid transport in plastids and mitochondria and provides an overview of the distinct tasks and features of members of the PRAT superfamily in the model plant Arabidopsis thaliana.