In several species there are two homologues of the E. coli serC gene, generally one in a ser operon (serC), and the other in a pdx operon, in which case it is called pdxF.
En varias especies hai dous homólogos do xene serC de E. coli, xeralmente un no operón ser, e outro no operón pdx, e nese caso é denominado pdxF.