title: Characterisation of two articulins, the major epiplasmic proteins comprising the membrane skeleton of the ciliate Pseudomicrothorax.
abstract: Most protists possess a unique membrane skeleton, the epiplasm, which is involved in pattern forming processes of the cell cortex and functions in maintaining cell shape. Articulins, a novel class of cytoskeletal proteins, are major constituents of the epiplasm. We have isolated cDNAs encoding the two major articulins of the ciliate Pseudomicrothorax dubius. Peptide sequence data confirm the identity of the cloned cDNAs encoding articulins 1 and 4. With the data presented here sequence information for all major articulins of ciliates as well as the distantly related euglenoids is available. Sequence comparison of the two newly characterised ciliate articulins with the previously determined sequences of p60, a minor articulin of the same species, and the two euglenoid articulins reveals general sequence principles and uncovers new features of this protein family. The hallmark of articulins is a central core domain of repetitive motifs of alternating valine and proline residues, the VPV-motif. These VPV-motif repeats are either 12-residues, or in some places, six residues long. Positively and negatively charged residues segregate in register with valine and proline positions. The VPV-motif is unique to articulins. The terminal domains flanking the core are generally hydrophobic and contain a series of hexa- or heptapeptide repeats rich in glycine and hydrophobic residues. The sequences of these short repeats are very similar in articulins of the same species but are not conserved between euglenoids and ciliates.
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Department of Biochemistry, Am Fassberg 11, D-37077 Göttingen, Federal Republic of Germany.
authors.forename: I
authors.initials: I
authors.lastname: Huttenlauch
authors.forename: R K
authors.initials: RK
authors.lastname: Peck
authors.forename: U
authors.initials: U
authors.lastname: Plessmann
authors.forename: K
authors.initials: K
authors.lastname: Weber
authors.forename: R
authors.initials: R
authors.lastname: Stick
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016798:Ciliophora / Q000737:chemistry / Q000378:metabolism*; D003001:Cloning, Molecular; D016384:Consensus Sequence; D003598:Cytoskeletal Proteins / Q000096:biosynthesis* / Q000737:chemistry*; D017931:DNA Primers; D018076:DNA, Complementary; D005056:Euglena gracilis / Q000378:metabolism; D015723:Gene Library; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000737:chemistry*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D015800:Protozoan Proteins / Q000096:biosynthesis / Q000737:chemistry*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D003598:Cytoskeletal Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D008565:Membrane Proteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C076623:articulin