This enzyme regulates the homeostasis of cellular adenine nucleotides by converting ADP into ATP and AMP 9 and thus may be critical in specific key subcellular or extracellular compartments.The PfAK2 N-terminus targets GFP to the outside of the parasite plasma membrane. (A) The AK21-37/GFP was expressed using the CRT promoter (construct indicated above the images). Live cell imaging of the PfAK21-37/GFP in trophozoite and schizont stages, showed a location of the GFP signal similar to that of PfAK2/GFP. In the schizont stage of these parasites a clear signal for the fusion protein was visible around each of the individual daughter merozoites. Details as in Fig 1. The AK21-37/GFP transgenic parasites were subjected to (B) hypotonic, or (C) SLO and saponin lysis and cell fractionation as described in Fig 2. The absence of the protein band corresponding to the PfAK21-37/GFP fusion protein in the saponin pellet fraction treated with Proteinase K indicates the secretion of the protein beyond the PPM. Thavayogarajah T, Gangopadhyay P, Rahlfs S, Becker K, Lingelbach K, Przyborski JM, Holder AA. Alternative Protein Secretion in the Malaria Parasite Plasmodium falciparum. PLoS One. 2015 PMID: 25909331;