Actin in the merozoite of the malaria parasite, Plasmodium falciparum

Cell Motil Cytoskeleton. 1993;25(1):43-8. doi: 10.1002/cm.970250106.


Merozoites of the human malaria parasite, Plasmodium falciparum, when treated with cytochalasin B, will attach irreversibly to red cells with formation of a vestigial internal (parasitophorous) vacuole, but they are inhibited from moving into the cell. The existence of an actin-based motile mechanism is implied. Immunoblotting, peptide mapping and the DNase inhibition assay have been used to show that the merozoite contains actin. It makes up an estimated 0.3% of the total parasite protein and is partitioned in the ratio of about 1:2 between the cytosolic and particulate protein fractions. In the former it is unpolymerised and in the latter filamentous. Most of the anti-actin-reactive protein in the soluble fraction and about 20% of that in the pellet has an apparent molecular weight of 55,000 and reacts with an anti-ubiquitin antibody; it is thus evidently ubiquitinyl actin, or arthrin, which has so far been detected only in insect flight muscle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / analysis*
  • Actins / chemistry
  • Animals
  • Biological Assay
  • Deoxyribonuclease I / antagonists & inhibitors
  • Humans
  • Molecular Weight
  • Plasmodium falciparum / chemistry*
  • Plasmodium falciparum / growth & development
  • Protozoan Proteins / analysis*
  • Ubiquitins / analysis


  • Actins
  • Protozoan Proteins
  • Ubiquitins
  • Deoxyribonuclease I