Many biomolecules come in two versions that are each other’s mirror image, like a left and a right hand. Cells generally use the left-hand version of amino acids to produce proteins, and uptake mechanisms were thought to share this preference. University of Groningen scientists have now shown that a prokaryotic transport protein can transport both versions of the amino acid aspartate with equal efficiency. Detailed analysis of the structure of the transporter shows why this is the case. The results were published in the journal eLife on 24 April.