Structural diversity in the 45-kilodalton merozoite surface antigen of Plasmodium falciparum.
An integral membrane protein associated with the merozoite surface of Plasmodium falciparum termed merozoite surface antigen 2 (the 45-kDa merozoite surface antigen), occurs in antigenically diverse forms. Here we report the sequences of the MSA 2 gene from two other isolates of P. falciparum. The 43 N-terminal residues and the 74 C-terminal residues of all three MSA 2 sequences are highly conserved, but between these conserved regions there are dramatic differences among the alleles. Instead of the two copies of a 32-amino-acid repeat present in the MSA 2 of isolate FC27, MSA 2 from clone 3D7 and isolate Indochina 1 contain 5 and 12 copies respectively of the four amino acid sequence Gly Gly Ser Ala. The sequences flanking the repeats also differ among the three antigens. The repeats in MSA 2 appear to be immunodominant during natural infection, and antibodies to the repeat regions of different alleles react with a restricted number of parasite isolates.
Smythe
J A
JA
Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia.
Peterson
M G
MG
Coppel
R L
RL
Saul
A J
AJ
Kemp
D J
DJ
Anders
R F
RF
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics* / Q000276:immunology; D000954:Antigens, Surface / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D005796:Genes; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics / Q000276:immunology*; D012091:Repetitive Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid
D000953:Antigens, Protozoan; D000954:Antigens, Surface