Microneme
Encyclopedia
Micronemes are cellular organs, or organelles, possessed by Apicomplexa
protozoans that are restricted to the apical third of the protozoan body. They are surrounded by a typical unit membrane. On electorn microscopy they have an electron-dense matrix due to the high protein content. They are specialized secretory organelles important for gliding motility
and host cell invasion.
These organelles secrete several proteins such as Plasmodium falciparum apical membrane antigen-1
, or PfAMA1, and Erythrocyte family antigen, or EBA, family proteins. These proteins specialize in binding to erythrocyte surface receptors and facilitating erythrocyte entry. Only by this initial chemical exchange can the parasite enter into the erythrocyte via actin-myosin motor complex. This is a crucial organelle for the P. falciparum parasite.
It has been posited that this organelle works cooperatively with its counterpart organelle, the rhoptry, which also is a secretory organelle. It is possible that, while the microneme initiates erythrocyte-binding, the rhoptry secretes proteins to create the PVM, or the Parasitophorous Vacuolar Membrane, in which the parasite can survive and reproduce.
Apicomplexa
The Apicomplexa are a large group of protists, most of which possess a unique organelle called apicoplast and an apical complex structure involved in penetrating a host's cell. They are unicellular, spore-forming, and exclusively parasites of animals. Motile structures such as flagella or...
protozoans that are restricted to the apical third of the protozoan body. They are surrounded by a typical unit membrane. On electorn microscopy they have an electron-dense matrix due to the high protein content. They are specialized secretory organelles important for gliding motility
Gliding motility
Gliding motility is a form of motility specific to apicomplexa that uses a large complex of proteins around the cell surface....
and host cell invasion.
These organelles secrete several proteins such as Plasmodium falciparum apical membrane antigen-1
Apical membrane antigen 1
In molecular biology, apical membrane antigen 1 is a novel antigen of Plasmodium falciparum which has been cloned. It contains a hydrophobic domain typical of an integral membrane protein. The antigen is designated apical membrane antigen 1 by virtue of appearing to be located in the apical complex...
, or PfAMA1, and Erythrocyte family antigen, or EBA, family proteins. These proteins specialize in binding to erythrocyte surface receptors and facilitating erythrocyte entry. Only by this initial chemical exchange can the parasite enter into the erythrocyte via actin-myosin motor complex. This is a crucial organelle for the P. falciparum parasite.
It has been posited that this organelle works cooperatively with its counterpart organelle, the rhoptry, which also is a secretory organelle. It is possible that, while the microneme initiates erythrocyte-binding, the rhoptry secretes proteins to create the PVM, or the Parasitophorous Vacuolar Membrane, in which the parasite can survive and reproduce.