Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An endoplasmic reticulum-located, calcium-binding protein, with an apparent molecular weight (Mr) of approximately 40,000 (PfERC), has been identified in the asexual stages of the malaria parasite, Plasmodium falciparum. This protein appears to be equivalent to a previously described gametocyte protein, Pfs40, which was reported to be expressed on the gametocyte surface (Rawlings DJ, Kaslow DC. J Biol Chem 1992;267:3976-3982). Sequencing of the 3' end of the gene revealed the omission of a single base in the 3' region of the published sequence. The corrected gene sequence encodes a C-terminal IDEL motif, which indicates residency of the 40 kDa protein within the endoplasmic reticulum. The predicted C-terminal region also appears to contain a sixth EF-hand calcium-binding domain, which suggests that PfERC is related to previously reported ER-localized calcium-binding proteins, namely reticulocalbin and ERC-55 (Ozawa M. J. Biochem. 1995;117:1113-1119; Weis K, Griffiths G, Lamond AI. J. Biol. Chem. 1994;269:19142-19150). The presence of the 40 kDa calcium-binding protein in malaria parasites was confirmed using 45Ca2+-blotting and partial protein sequencing of the corresponding Coomassie blue-stained polypeptide. Confocal immunofluorescence microscopy of asexual stage parasites was used to show that PfERC co-localizes with the known ER-located protein, Pfgrp. Analysis of immunoblots of tightly synchronized parasites showed that expression of PfERC increases with increasing maturity of the parasite. We propose that PfERC is a member of the reticulocalbin family of calcium-binding proteins and may play a role in protein trafficking in the malaria parasite.
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PMID:Identification of an endoplasmic reticulum-resident calcium-binding protein with multiple EF-hand motifs in asexual stages of Plasmodium falciparum. 936 72

To the malaria parasite, the prospect of setting up residence within a human erythrocyte represents a formidable challenge. The mature human erythrocyte is essentially a bag of haemoglobin with no internal organelles and no protein synthesis machinery. The parasite needs, therefore, to assemble all the essential amenities--foundations, plumbing and furnishings--from scratch. The parasite remodels its adopted home by exporting proteins to the erythrocyte membrane. To reach their final destinations, the exported proteins must cross the parasite plasma membrane, the parasitophorous vacuole membrane and the erythrocyte cytosol. To further understand this unusual and complex trafficking pathway, we have searched for proteins that may form part of the trafficking machinery of the infected erythrocyte. We have identified an ER-located, calcium-binding homologue of reticulocalbin (PfERC) that co-localizes with the ER molecular chaperone, PfGRP. We have also identified a homologue of the GTP-binding protein, Sar1p, a small GTPase that, in other eukaryotic cells, is thought to play a crucial role in trafficking proteins between the ER and the Golgi. PfSar1p is located in discrete structures near the periphery of the parasite cytoplasm that may represent specialized export compartments. PfSar1p is exported to structures outside the parasite in the erythrocyte cytoplasm. The malaria parasite appears to be capable of elaborating components of the 'classical' vesicle mediated trafficking machinery outside the boundaries of its own plasma membrane.
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PMID:Export of parasite proteins to the erythrocyte cytoplasm: secretory machinery and traffic signals. 1064 45