title: Intracellular calcium channels in protozoa.
abstract: Ca(2+)-signaling pathways and intracellular Ca(2+) channels are present in protozoa. Ancient origin of inositol 1,4,5-trisphosphate receptors (IP3Rs) and other intracellular channels predates the divergence of animals and fungi as evidenced by their presence in the choanoflagellate Monosiga brevicollis, the closest known relative to metazoans. The first protozoan IP3R cloned, from the ciliate Paramecium, displays strong sequence similarity to the rat type 3 IP3R. This ciliate has a large number of IP3- and ryanodine(Ry)-like receptors in six subfamilies suggesting the evolutionary adaptation to local requirements for an expanding diversification of vesicle trafficking. IP3Rs have also been functionally characterized in trypanosomatids, where they are essential for growth, differentiation, and establishment of infection. The presence of the mitochondrial calcium uniporter (MCU) in a number of protozoa indicates that mitochondrial regulation of Ca(2+) signaling is also an early appearance in evolution, and contributed to the discovery of the molecular nature of this channel in mammalian cells. There is only sequence evidence for the occurrence of two-pore channels (TPCs), transient receptor potential Ca(2+) channels (TRPCs) and intracellular mechanosensitive Ca(2+)-channels in Paramecium and in parasitic protozoa.
authors.affiliation: Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, GA 30606, USA. Electronic address: rdocampo@uga.edu.
authors.forename: Roberto
authors.initials: R
authors.lastname: Docampo
authors.affiliation: Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, GA 30606, USA.
authors.forename: Silvia N J
authors.initials: SN
authors.lastname: Moreno
authors.affiliation: Department of Biology, University of Konstanz, P.O. Box M625, Konstanz 78457, Germany. Electronic address: helmut.plattner@uni-konstanz.de.
authors.forename: Helmut
authors.initials: H
authors.lastname: Plattner
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000378:metabolism*; D016798:Ciliophora / Q000166:cytology / Q000378:metabolism; D042541:Intracellular Space / Q000378:metabolism*; D010271:Parasites / Q000166:cytology / Q000378:metabolism; D015800:Protozoan Proteins / Q000378:metabolism*
chemical_list: D015220:Calcium Channels; D015800:Protozoan Proteins
keywords: Calcium channels; Mitochondrial calcium uniporter; Paramecium; Protozoa; Toxoplasma; Trypanosoma