Protein S-palmitoylation is an important post-translational modification (PTM) 
in blood stages of the malaria parasite, Plasmodium falciparum. S-palmitoylation 
refers to reversible covalent modification of cysteine residues of proteins by 
saturated fatty acids. In vivo, palmitoylation is regulated by concerted 
activities of DHHC palmitoyl acyl transferases (DHHC PATs) and acyl protein 
thioesterases (APTs), which are enzymes responsible for protein palmitoylation 
and depalmitoylation, respectively. Here, we investigate the role of protein 
palmitoylation in red blood cell (RBC) invasion by P. falciparum merozoites. We 
demonstrate for the first time that free merozoites require PAT activity for 
microneme secretion in response to exposure to the physiologically relevant low 
[K+] environment, characteristic of blood plasma. We have adapted copper 
catalyzed alkyne azide chemistry (CuAAC) to image palmitoylation in merozoites 
and found that exposure to low [K+] activates PAT activity in merozoites. 
Moreover, using acyl biotin exchange chemistry (ABE) and confocal imaging, we 
demonstrate that a calcium dependent protein kinase, PfCDPK1, an essential 
regulator of key invasion processes such as motility and microneme secretion, 
undergoes dynamic palmitoylation and localizes to the merozoite membrane. 
Treatment of merozoites with the PAT inhibitor, 2-bromopalmitate (2-BP), 
effectively inhibits microneme secretion and RBC invasion by the parasite, thus 
opening the possibility of targeting P. falciparum PATs for antimalarial drug 
discovery to inhibit blood stage growth of malaria parasites.