loop_ _pdbx_struct_assembly_auth_evidence_depositor_info.id _pdbx_struct_assembly_auth_evidence_depositor_info.assembly_id _pdbx_struct_assembly_auth_evidence_depositor_info.experimental_support _pdbx_struct_assembly_auth_evidence_depositor_info.details 1 1 'cross-linking' . 2 1 'gel filtration' 'Elutes as a dimer' 3 2 'cross-linking' .