The S-antigen of Plasmodium falciparum: repertoire and origin of diversity.
S-antigens are heat-stable, highly polymorphic proteins released by Plasmodium falciparum at the time of schizont rupture. Previously determined S-antigen sequences allowed the proposal of a general gene structure consisting of 5 sequence blocks. The sequence of the central block of tandem repeats provides a useful means of distinguishing the S-antigen allele and also its serotype, whereas the amino and carboxy terminal sequences defined the S-antigen family, 4 of which have been described. We present the sequence of 3 new S-antigen alleles, for the isolates HB3, KF1916 and KF1917. The allele-defining repeat sequence is ETGPGKAGEQG for HB3, GDQTEGS(S/A)GGK for KF1917 and AGSNE(E/K) for KF1916. The sequences of these newly described S-antigens are consistent with the proposed general gene structure and all belong to defined families, although carboxy-terminal sequences appear to be much more variable within a family than previously realised.
Bickle
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Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.
Anders
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Day
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Coppel
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D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D000954:Antigens, Surface / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D001483:Base Sequence; D016384:Consensus Sequence; D017931:DNA Primers; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics / Q000276:immunology*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid
D000953:Antigens, Protozoan; D000954:Antigens, Surface; D017931:DNA Primers