ATG7 acts as an E1-like enzyme for ATG12. It binds to and activates ATG12, allow its transfer to the E2-like ATG10.
The amino-acid sequence of ATG12 ends with a glycine residue and does not require protease activation. ATG12 is activated by forming a thioester bond between its C-terminal Gly-140 and Cys-572 of ATG7 (Tanida et al. 1999, 2001). ATG7 has been shown to function in the form of a homodimer (Komatsu et al. 2001).