Cloning of glycoprotein D cDNA, which encodes the major subunit of the Duffy blood group system and the receptor for the Plasmodium vivax malaria parasite.

Abstract

cDNA clones encoding the major subunit of the Duffy blood group were isolated from a human bone marrow cDNA library using a PCR-amplified DNA fragment encoding an internal peptide sequence of glycoprotein D (gpD) protein. The open reading frame of the 1267-bp cDNA clone indicated that gpD protein was composed of 338 amino acids, predicting a M(r) of 35,733, which was the same as a deglycosylated gpD protein. Portions of the predicted amino acid sequence, matched with six CNBr/pepsin peptides obtained from affinity-purified gpD protein. In ELISA analysis, an anti-Duffy murine monoclonal antibody reacted with a synthetic peptide deduced from the cDNA clone. Hydropathy analysis suggested the presence of 9 membrane-spanning alpha-helices. In bone marrow RNA blot analysis, the gpD cDNA detected a 1.27-kb mRNA in Duffy-positive but not in Duffy-negative individuals. It also identified the same size mRNA in adult kidney, adult spleen, and fetal liver; in brain, it detected a prominent 8.5-kb and a minor 2.2-kb mRNA. In Southern blot analysis, gpD cDNA identified a single gene in Duffy-positive and -negative individuals. Duffy-negative individuals, therefore, have the gpD gene, but it is not expressed in bone marrow. The same or a similar gene is active in adult kidney, adult spleen, and fetal liver of Duffy-positive individuals. Whether this is true in Duffy-negative individuals remains to be demonstrated. A GenBank sequence search yielded a significant protein sequence homology to human and rabbit interleukin-8 receptors.