passages.id: split_4_validation_1507_passage
passages.type: progene_text
passages.text: To understand the molecular basis of this receptor - ligand recognition , we have crystallized the extracellular ligand - binding domains of KIR2DL2 , a member of the Ig superfamily receptors that recognize HLA-Cw1 , 3 , 7 , and 8 allotypes .