SNAREs (soluble N-ethylmaleimide-sensitive element attachment protein receptors) play a central role

SNAREs (soluble N-ethylmaleimide-sensitive element attachment protein receptors) play a central role in regulating and facilitating vesicular traffic in eukaryotic cells. such as syntaxin 1. This is the first identified trafficking component localized proximal to the plasma membrane. species are a diverse and extremely successful group of intracellular parasites which in humans cause 300-500 million cases and more than 1 million deaths from malaria each year [1]. The majority of human malaria mortality is usually caused by parasites has a complex life cycle involving both mosquito and human hosts. This complicated life cycle depends on a vast array of parasite-host interactions and many of these interactions are controlled by the secretory pathway. For example during the intra-erythrocytic stage of development which is the stage that causes all the symptoms and pathology of malaria it is the secretory pathway that ingests hemoglobin from the erythrocyte cytosol to drive parasite growth and replication and it is the secretory pathways that traffics antigenically variable cytoadherence ligands to the erythrocyte plasma membrane to avoid the protective immune response. Work on model organisms and cell lines has revealed a great deal LY404039 about the molecular mechanisms of secretion and both preliminary genome analysis and recent elegant mechanistic LY404039 studies [2 3 have confirmed that many of these fundamental features of eukaryotic secretory pathways are conserved in intra-erythrocytic stages also contain several unique organelles that are not readily classifiable into the classical eukaryotic secretory pathway. First a food vacuole begins to form during the ring stage where endocytosed hemoglobin is LY404039 usually transported to and then metabolized [4 5 Second possesses an apicoplast a non-photosynthetic plastid where fatty acids are synthesized and is unique to the phylum Apicomplexa [6 7 Third after invasion of the host erythrocyte unique membrane-bound organelles called Maurer’s clefts develop outside of the parasites own plasma membrane in the erythrocyte cytosol and appear to play a role in trafficking proteins to the erythrocyte plasma membrane [8]. It is currently not known how any of these organelles intersect with the classical eukaryotic secretory pathway. Organelles maintain a distinct identity because protein transport to them is usually LY404039 a tightly controlled event. Proteins are transported between organelles by in membrane-bound vesicles and the direction and specificity of vesicle transport is usually governed in large part by two families of proteins SNAREs and Rabs. Rabs are small GTPases of the LY404039 Ras superfamily that cycle between the cytosol (GDP bound) and organelle membranes (GTP bound) and Rab effector proteins aid in vesicle tethering as well as specificity of vesicle VWF fusion [reviewed in 9]. Eleven Rab gene homologues have already been determined in [10]. SNAREs certainly are a category of typically membrane destined protein that are characterized by a comparatively conserved coiled-coil SNARE area close to the C-terminus [11 evaluated in 12] and will be functionally categorized as v-SNARES which can be found on vesicles or t-SNARES which can be found on a focus on organelle. Another nomenclature divides the SNAREs into Q-SNAREs and R-SNAREs based on the presence of the glutamine or arginine residue at the primary from the SNARE area. Q-SNAREs are additional subdivided into Qa- Qb- and Qc-SNAREs with Qa-SNAREs having homology to syntaxin 1a the neuronal plasma membrane proteins utilized to define the t-SNARE course [13]. Membrane fusion takes place LY404039 when 3 Q-SNARE domains and one R-SNARE area come together to create tetrameric helical pack complicated that drives the fusion between your vesicle and focus on area [14]. SNAREs have already been within the genomes of most eukaryotes researched to date through the primitive one celled to [15] as well as the released genome of contains many sequences with homology to SNARE domains. An initial evaluation of such sequences identified 18 members of the SNARE family in [16] and noted several unusual features of these sequences but did not classify such sequences into Qa- Qb- Qc- and R-SNARE sub-families. Because of their role in specifying the fidelity of vesicle fusion and presence primarily on organelles rather than vesicles Qa-SNAREs are of particular interest as organelle markers. Given the presence of several organelles of unknown provenance in.