PMID-sentid Pub_year Sent_text comp_official_name comp_offsetprotein_name organism prot_offset 1648965-6 1991 It is further proposed that those ligands with two phosphonate groups can simultaneously bind to cationic amino acid side chains that extend into the cleft between the two domains of each lobe of transferrin. Organophosphonates 51-62 transferrin Homo sapiens 196-207