Cytosine Permease

Cytosine permease is a transmembrane protein responsible for the active transport of cytosine across the cell membrane. It is found in various organisms, including bacteria such as *Escherichia coli* (where it is encoded by the codB gene) and yeast such as *Saccharomyces cerevisiae* (encoded by the FCY2 gene). In yeast, this transporter has broad substrate specificity: it transports purines (adenine, guanine, hypoxanthine), cytosine, and 5-methylcytosine but does not transport uracil or thymine. Transport occurs via an active mechanism that utilizes a proton electrochemical gradient as an energy source. It may also play roles in drug import/export due to its ability to recognize structurally similar molecules; this has implications in antifungal drug resistance research in yeast models.

Other names

codB proteinFCY2 proteinPurine-cytosine permease (PCP)