ELSEVIER Multiple genes code for high-molecular-mass rhoptry proteins of zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDC Plasmodium y oelii Martin B. Borre ‘, Carolyn A. Owen ‘, Jane K. Keen 3, Katharine A. Sinha 4, Anthony A. Holder * Molecular and Biochemical Parasitology 70 (1995) 149-155 MOLECULAR iEHEMIcAL PARASITOLOGY zyxwvu Division of Parasitology, National Institute for Medical Research, Mill Hill, London NW7 IAA, UK Received 1 September 1994; accepted 24 January 1995 zyxwvutsrqponmlkjihgfedcbaZYXWVUTS Abstract We have examined the number of genes coding for a group of high-molecular-mass rhoptry protein(s) in the malaria parasite Plasmodium yoelii, and studied variation in the gene family within the parasite’s genome. A region of the genes was amplified using oligonucleotides based on conserved DNA sequences and the products cloned. The sequences could be divided into 7 groups by restriction-fragment-length polymorphism. Further variation was detected by sequence analysis; 11 different sequences were detected in the 16 clones analyzed. The genes in the family were distributed on 6 chromosomes probably at 9 or more loci. Keywords: Rhoptry protein; Multigene family; Plasmodium yoelii; Malaria Abbreuiations: PBS, phosphate-buffered saline; PCR, poly- merase chain reaction. Note: Nucleotide sequence data reported in this paper are available in the EMBL, GenBankTM and DDJB data bases under the accession numbers IJ19979 to U19992. * Corresponding author. Tel.: (44-81) 959-3666 ext. 2175; Fax: (44-81) 913-8593; e-mail: a-holder@nimr.mrc.ac.uk 1 Present address: Molecular Biology Laboratory, Statens Seruminstitut, DK-2300 Copenhagen, Denmark. ’ Present address: Parasitology Department, The Hellenic Pas- teur Institute, Athens 115-21, Greece. 3 Present address: Wellcome Centre for Parasitic Infections, Department of Biochemistry, Imperial College of Science, Tech- nology and Medicine, London SW7 2AY, UK. 4 Present address: Department of Microbiology, The Medical School, University of Newcastle, Newcastle NE2 4HH, UK 1. Introduction A 235kDa protein has been identified in zyxwvutsrqponml Plas- modium yoelii using monoclonal antibodies that re- acted with an antigen in the rhoptry organelles of the merozoite [1,2]. On passive transfer these antibodies protected mice against challenge with the virulent YM strain, and confined the parasites to reticulocytes during the period of infection [3]. Recently the pro- tein has been resolved further into a group of polypeptides partially separated by SDS-PAGE 141. DNA clones coding for a small part of the C-terminus of the rhoptry protein(s) have also been identified [S]; this work indicated’that there is more than one copy of the gene in the P. yoelii genome, since different but related sequences were obtained from three independent clones. Two clones (designated E3 0166-6851/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 0166-6851(95)00025-9