Primary structure and sexual stage-specific expression of a LAMMER protein kinase of Plasmodium falciparum

We have isolated a LAMMER-like gene from Plasmodium falciparum by vectorette technique. The gene consists of 3316 bp encoding a protein 881 amino acids with a predicted molecular mass of approximately 106.7 kDa. The encoded protein, termed PfLAMMER, is composed of two distinct domains. The N-terminal domain is not related to any previously described protein kinases and has several interesting features including multiple consensus phosphorylation sites for a range of protein kinases, a number of RS/SR dipeptides, a large proportion of charged amino acids, two putative nuclear localisation signals and 14 copies of a tetramer DKYD repeats. The C-terminal domain is characteristic of a kinase in the LAMMER family with the highest homology to the Arabidopsis thaliana AFC3 kinase. Genomic restriction analysis showed that PfLAMMER is encoded by a single copy gene in the parasite genome. A single transcript of approximately 3800 nucleotides is expressed specifically in the sexual stage, indicating that PfLAMMER may be important in regulating the processes of sexual differentiation of the parasite.