USE OF DOMAIN-DELETION MUTANTS TO LOCATE LUTHERAN BLOOD-GROUP ANTIGENS TO EACH OF THE 5 IMMUNOGLOBULIN SUPERFAMILY DOMAINS OF THE LUTHERAN GLYCOPROTEIN - ELUCIDATION OF THE MOLECULAR-BASIS OF THE LU-A LU-B ANDTHE AU-A/AU-B POLYMORPHISMS/

Lutheran glycoprotein (Lu gp) has five predicted immunoglobulin superf amily (IgSF) domains. K562 cells were transfected with Lu cDNA and tes ted by flow cytometry with monoclonal antibodies and Lu blood group an tisera, The results confirmed the identity of Lu cDNA. Deletion mutant s lacking the regions encoding one or more IgSF domains were made by i nverse polymerase chain reaction (PCR), expressed in K562 cells, and t ested with the same antibodies. The Lu-b and Lu5 antigens and the epit ope recognized by monoclonal antibody BRIC 224 were mapped to the firs t, N-terminal, IgSF domain. Lu4 and Lu8 were mapped to domain 2; Lu20 to domain 3; Lu7 and BRIC 221 epitope to domain 4, and Lu13 and Au-b t o domain 5. The organization of the LU gene was determined. The region encoding the open reading frame is arranged in 15 exons extending ove r approximate to 11 kb on chromosome 19q13.2. The Lu-a/Lu-b and Au-a/A u-b blood group polymorphisms were studied using genomic DNA from type d blood donors. The Lu-a mutation is a base change in exon 3 (G(252) t o A) encoding an Arg(77) (Lu-b) to His (Lu-a) change on the CFG face o f domain 1. The Au-a/Au-b polymorphism is an A(1637) to G substitution in exon 12 encoding a Thr(539) (Au-a) to Ala (Au-b) change on the G s trand of domain 5. (C) 1997 by The American Society of Hematology.