title: Xenopus laevis RIC-3 enhances the functional expression of the C. elegans homomeric nicotinic receptor, ACR-16, in Xenopus oocytes.
abstract: RIC-3 enhances the functional expression of certain nicotinic acetylcholine receptors (nAChRs) in vertebrates and invertebrates and increases the availability of functional receptors in cultured cells and Xenopus laevis oocytes. Maximal activity of RIC-3 may be cell-type dependent, so neither mammalian nor invertebrate proteins is optimal in amphibian oocytes. We cloned the X. laevis ric-3 cDNA and tested the frog protein in oocyte expression studies. X. laevis RIC-3 shares 52% amino acid identity with human RIC-3 and only 17% with that of Caenorhabditis elegans. We used the C. elegans nicotinic receptor, ACR-16, to compare the ability of RIC-3 from three species to enhance receptor expression. In the absence of RIC-3, the proportion of oocytes expressing detectable nAChRs was greatly reduced. Varying the ratio of acr-16 to X. laevis ric-3 cRNAs injected into oocytes had little impact on the total cell current. When X. laevis, human or C. elegans ric-3 cRNAs were co-injected with acr-16 cRNA (1 : 1 ratio), 100 μM acetylcholine induced larger currents in oocytes expressing X. laevis RIC-3 compared with its orthologues. This provides further evidence for a species-specific component of RIC-3 activity, and suggests that X. laevis RIC-3 is useful for enhancing the expression of invertebrate nAChRs in X. laevis oocytes.
authors.affiliation: Department of Infectious Diseases and Center for Tropical & Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA.
authors.forename: Hayley M
authors.initials: HM
authors.lastname: Bennett
authors.forename: Kristin
authors.initials: K
authors.lastname: Lees
authors.forename: Kate M
authors.initials: KM
authors.lastname: Harper
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Jones
authors.forename: David B
authors.initials: DB
authors.lastname: Sattelle
authors.forename: Susan
authors.initials: S
authors.lastname: Wonnacott
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Wolstenholme
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology*; D018832:Molecular Chaperones / Q000502:physiology*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism* / Q000502:physiology; D011978:Receptors, Nicotinic / Q000096:biosynthesis* / Q000235:genetics* / Q000502:physiology; D015854:Up-Regulation / Q000235:genetics*; D029867:Xenopus Proteins / Q000502:physiology*; D014982:Xenopus laevis; D064569:alpha7 Nicotinic Acetylcholine Receptor
chemical_list: D029742:Caenorhabditis elegans Proteins; C579167:Chrna7 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; C578269:RIC3 protein, Xenopus; D011978:Receptors, Nicotinic; D029867:Xenopus Proteins; C099378:acr-16 protein, C elegans; D064569:alpha7 Nicotinic Acetylcholine Receptor; C454141:ric-3 protein, C elegans