title: Extracellular proteins needed for C. elegans mechanosensation.
abstract: The mec-5 and mec-9 genes encode putative extracellular proteins that allow a set of six touch receptor neurons in C. elegans to respond to gentle touch. MEC-5 is a collagen made by the epidermal cells that surround the touch cells. Mutations causing touch insensitivity affect the Gly-X-Y repeats of this collagen. mec-9 produces two transcripts, the larger of which is expressed in the touch cells and two PVD neurons. This transcript encodes a protein with 5 Kunitz-type protease inhibitor domains, 6 EGF-like repeats (2 of the Ca(2+)-binding type), and a glutamic acid-rich region. Missense mutations causing touch insensitivity affect both the EGF-like and Kunitz domains. Since mec-9 loss of function mutations dominantly enhance the touch insensitive phenotype of several mec-5 mutations, MEC-5 and MEC-9 may interact. We propose that these proteins provide an extracellular attachment point for the mechanosensory channels of the touch cells.
authors.affiliation: Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
authors.forename: H
authors.initials: H
authors.lastname: Du
authors.forename: G
authors.initials: G
authors.lastname: Gu
authors.forename: C M
authors.initials: CM
authors.lastname: William
authors.forename: M
authors.initials: M
authors.lastname: Chalfie
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins; D003094:Collagen / Q000235:genetics / Q000502:physiology*; D004843:Epistasis, Genetic; D005109:Extracellular Matrix / Q000502:physiology*; D016326:Extracellular Matrix Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D005456:Fluorescent Dyes; D017238:Genes, Helminth; D005808:Genes, Recessive; D017930:Genes, Reporter; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D008465:Mechanoreceptors / Q000502:physiology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009475:Neurons, Afferent / Q000737:chemistry / Q000502:physiology*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000032:analysis; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014110:Touch / Q000502:physiology*
chemical_list: D029742:Caenorhabditis elegans Proteins; D016326:Extracellular Matrix Proteins; D005456:Fluorescent Dyes; D015801:Helminth Proteins; C097914:MEC-5 protein, C elegans; C097913:MEC-9 protein, C elegans; D011993:Recombinant Fusion Proteins; D003094:Collagen