Red blood cell proteomics.

Since its discovery in the 17th century, the red blood cell, recognized in time as the critical cell component for survival, has been the focus of much attention. Its unique role in gas exchange (oxygen/CO(2) transport) and its distinct characteristics (absence of nucleus; biconcave cell shape) together with an - in essence - unlimited supply lead to extensive targeted biochemical, molecular and structural studies. A quick PubMed query with the word "erythrocyte" results in 198 013 scientific articles of which 162 are red blood cell proteomics studies, indicating that this new technique has been only recently applied to the red blood cell and related fields. Standard and comparative proteomics have been widely used to study different blood components. A growing body of proteomics literature has since developed, which deals with the characterization of red blood cells in health and disease. The possibility offered by proteomics to obtain a global snapshot of the whole red blood cell protein make-up, has provided unique insights to many fields including transfusion medicine, anaemia studies, intra-red blood cell parasite biology and translational research. While the contribution of proteomics is beyond doubt, a full red blood cell understanding will ultimately require, in addition to proteomics, lipidomics, glycomics, interactomics and study of post-translational modifications. In this review we will briefly discuss the methodology and limitations of proteomics, the contribution it made to the understanding of the erythrocyte and the advances in red blood cell-related fields brought about by comparative proteomics.

The genome of the simian and human malaria parasite Plasmodium knowlesi.

Plasmodium knowlesi is an intracellular malaria parasite whose natural vertebrate host is Macaca fascicularis (the 'kra' monkey); however, it is now increasingly recognized as a significant cause of human malaria, particularly in southeast Asia. Plasmodium knowlesi was the first malaria parasite species in which antigenic variation was demonstrated, and it has a close phylogenetic relationship to Plasmodium vivax, the second most important species of human malaria parasite (reviewed in ref. 4). Despite their relatedness, there are important phenotypic differences between them, such as host blood cell preference, absence of a dormant liver stage or 'hypnozoite' in P. knowlesi, and length of the asexual cycle (reviewed in ref. 4). Here we present an analysis of the P. knowlesi (H strain, Pk1(A+) clone) nuclear genome sequence. This is the first monkey malaria parasite genome to be described, and it provides an opportunity for comparison with the recently completed P. vivax genome and other sequenced Plasmodium genomes. In contrast to other Plasmodium genomes, putative variant antigen families are dispersed throughout the genome and are associated with intrachromosomal telomere repeats. One of these families, the KIRs, contains sequences that collectively match over one-half of the host CD99 extracellular domain, which may represent an unusual form of molecular mimicry.