Secondary transporters are the simplest ones among biological systems that transport solutes across biological membranes. All they do, and some not even this, is to couple the translocation of a substrate to the translocation of one or more co-ions. This allows them to accumulate the substrate inside the cell. Maybe because of their simplicity, secondary transporters are very abundant in nature and found in all types of biological membranes, from prokaryotes to higher organisms. The project focuses on three aspects related to secondary transporters, (i) biochemical approaches to structure/function relationships of secondary transporter proteins, (ii) the function of the transporters in the physiology of the organism, (iii) bioinformatics & membrane proteins.