title: The Schistosoma mansoni Src kinase TK3 is expressed in the gonads and likely involved in cytoskeletal organization.
abstract: Cytoplasmic protein tyrosine kinases of the Src family play a pivotal role in the regulation of cellular processes including proliferation and differentiation. Among other functions, Src kinases are involved in regulating the cell architecture. In an approach to identify protein tyrosine kinases from the medically important parasite Schistosoma mansoni, we isolated the TK3 gene by degenerate primer PCR and cDNA library screening. Sequencing of the complete cDNA and data-base analyses indicated that TK3 is a Src family kinase. Its predicted size of 71 kDa was confirmed by Western blot analysis. Southern blot analysis showed that TK3 is a single-copy gene, and Northern blot and RT-PCR experiments indicated its expression in both sexes and throughout development. Localization studies by in situ hybridization and immunolocalization revealed that TK3 is predominantly expressed in the reproductive organs such as the testes of the male and the ovary as well as the vitellarium of the female. Its enzymatic activity was confirmed by functional analyses. In transient transfection experiments with HEK293 cells, TK3 phosphorylated the well-known Src-kinase substrate p130 Cas, an intracellular scaffolding protein. Yeast two-hybrid screenings in a heterologous invertebrate system identified dAbi, vinculin and tubulin as binding partners, representing molecules that fulfill functions in the cell architecture of many organisms. These findings suggest that TK3 may play a role in signal transduction pathways organizing the cytoskeleton in the gonads of schistosomes.
authors.affiliation: Institut für Genetik, Genetische Parasitologie und Biologisch-Medizinisches-Forschungszentrum, Universitätsstr. 1, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Kapp
authors.forename: Jürgen
authors.initials: J
authors.lastname: Knobloch
authors.forename: Peter
authors.initials: P
authors.lastname: Schüssler
authors.forename: Stefan
authors.initials: S
authors.lastname: Sroka
authors.forename: Reiner
authors.initials: R
authors.lastname: Lammers
authors.forename: Werner
authors.initials: W
authors.lastname: Kunz
authors.forename: Christoph G
authors.initials: CG
authors.lastname: Grevelding
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003599:Cytoskeleton / Q000502:physiology; D018509:DNA, Helminth / Q000737:chemistry / Q000302:isolation & purification; D005786:Gene Expression Regulation; D006066:Gonads / Q000201:enzymology; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016366:Open Reading Frames; D010802:Phylogeny; D011485:Protein Binding; D012550:Schistosoma mansoni / Q000201:enzymology*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology; D014404:Tubulin / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D016596:Vinculin / Q000378:metabolism; D019061:src-Family Kinases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D018509:DNA, Helminth; D015801:Helminth Proteins; D014404:Tubulin; D016596:Vinculin; D019061:src-Family Kinases