A naturally occurring gene encoding the major surface antigen precursor p190 of Plasmodium falciparum lacks tripeptide repeats.

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Abstract
Plasmodium falciparum merozoites have variable surface proteins that are processed from a 190‐kd precursor protein (p190). The gene encoding p190 exists in two allelic forms and cross‐over events occurring mainly near the 5′ end, combined with isolate‐specific tripeptide repeats, contribute to its antigen diversity. We have sequenced a large portion of the p190 gene from the parasite isolate RO‐33 (Ghana). Remarkably, the typical N‐terminal tripeptide repeat structure is lacking. Apart from mutations in the variable parts, the gene appears identical to the MAD‐20 allele (Papua, New Guinea). Southern blot analysis detects p190 genes similar to RO‐33 in other parasite isolates independent of their geographical origin. The lack of p190 repeats in RO‐33 eliminates the possibility that they are involved in host cell recognition or integration and restricts their function to immune escape.