title: The annexins of Dictyostelium.
abstract: Annexins are a highly conserved ubiquitous family of Ca2+- and phospholipid-binding proteins present in nearly all eukaryotic cells. Analysis of the Dictyostelium genome revealed the presence of two annexin genes, the annexin C1 gene (nxnA) giving rise to two isoforms of 47 and 51 kDa (previously synexin), and the annexin C2 gene (nxnB) coding for a 56-kDa protein with 33% sequence identity to annexin C1. Annexin C2 is expressed at very low and constant levels throughout development. Quantification by real-time PCR indicated that it is present in about 35-fold lower amounts compared to annexin C1. We have used a GFP-tagged annexin C2 to study its cellular distribution and dynamics. In cell fractionation studies, annexin C2 cofractionates with annexin C1 and is enriched in the 100,000 g pellet. Like annexin C1, GFP-AnxC2 stains the plasma membrane. In addition it is present in the perinuclear region and overlaps to some degree with the Golgi apparatus, whereas annexin C1 is present on intracellular membranes resembling endosomal membranes and in the nucleus. Annexin C2 is not observed in the nucleus. An annexin C1 mutant (SYN-) which shows a defect during multicellular development can be rescued by full-length annexin C1, whereas overexpression of GFP-AnxC2 did not rescue the developmental defect The data support the concept that annexins, although having a highly conserved structure, participate in different functions in a cell.
authors.affiliation: Institute for Biochemistry I, Medical Faculty, and Center for Molecular Medicine Cologne, University of Cologne, Joseph-Stelzmann-Str. 52, D-50931 Köln, Germany.
authors.forename: Marija
authors.initials: M
authors.lastname: Marko
authors.forename: Yogikala
authors.initials: Y
authors.lastname: Prabhu
authors.forename: Rolf
authors.initials: R
authors.lastname: Müller
authors.forename: Rosemarie
authors.initials: R
authors.lastname: Blau-Wasser
authors.forename: Michael
authors.initials: M
authors.lastname: Schleicher
authors.forename: Angelika A
authors.initials: AA
authors.lastname: Noegel
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017302:Annexins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D004023:Dictyostelium / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D017302:Annexins; D020033:Protein Isoforms; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D006180:Proton-Translocating ATPases