Rational Discovery of New Folds for Human Solute Carrier Proteins

Solute carrier superfamily (SLC) is the largest group responsible for transmembrane transport of substances in human cells. It includes more than 400 members that can be divided into 65 families according to their physiological function and sequence similarity. Different families of solute transporters can adopt the same or different folds that determines the working mechanism and reflects the evolutionary relationship between SLC members. Analysis of structural data in literatures shows that there are 13 different folds in the solute carrier superfamily covering 40 families and 343 members. To further study their working mechanism, we systematically explored the SLC superfamily to find more folds. Our results indicate that there are at least three new folds in the solute transporter superfamily among which the SLC44 family is experimentally verified to adopt a new fold. Our work has laid a foundation and provided important insights for the systematic and comprehensive study on the structure and function of solute carriers.