The ligandin (non-substrate) binding site of human Pi class glutathione transferase is located in the electrophile binding site (H-site).
Oakley, A.J., Lo Bello, M., Nuccetelli, M., Mazzetti, A.P., Parker, M.W.(1999) J Mol Biol 291: 913-926
- PubMed: 10452896 
- DOI: 10.1006/jmbi.1999.3029
- Primary Citation of Related Structures:  
12GS, 13GS, 18GS, 19GS, 20GS - PubMed Abstract: 
Glutathione S -transferases (GSTs) play a pivotal role in the detoxification of foreign chemicals and toxic metabolites. They were originally termed ligandins because of their ability to bind large molecules (molecular masses >400 Da), possibly for storage and transport roles ...