title: A novel SDS-stable dimer of a heterogeneous nuclear ribonucleoprotein at presynaptic terminals of squid neurons.
abstract: The presence of mRNAs in synaptic terminals and their regulated translation are important factors in neuronal communication and plasticity. Heterogeneous nuclear ribonucleoprotein (hnRNP) complexes are involved in the translocation, stability, and subcellular localization of mRNA and the regulation of its translation. Defects in these processes and mutations in components of the hnRNP complexes have been related to the formation of cytoplasmic inclusion bodies and neurodegenerative diseases. Despite much data on mRNA localization and evidence for protein synthesis, as well as the presence of translation machinery, in axons and presynaptic terminals, the identity of RNA-binding proteins involved in RNA transport and function in presynaptic regions is lacking. We previously characterized a strongly basic RNA-binding protein (p65), member of the hnRNPA/B subfamily, in squid presynaptic terminals. Intriguingly, in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), p65 migrated as a 65-kDa protein, whereas members of the hnRNPA/B family typically have molecular masses ranging from 35 to 42kDa. In this report we present further biochemical and molecular characterization that shows endogenous p65 to be an SDS-stable dimer composed of ∼37-kDa hnRNPA/B-like subunits. We cloned and expressed a recombinant protein corresponding to squid hnRNPA/B-like protein and showed its propensity to aggregate and form SDS-stable dimers in vitro. Our data suggest that this unique hnRNPA/B-like protein co-localizes with synaptic vesicle protein 2 and RNA-binding protein ELAV and thus may serve as a link between local mRNA processing and presynaptic function and regulation.
authors.affiliation: Department of Cellular & Molecular Biology, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo 14049-900, Brazil; Marine Biological Laboratory, Woods Hole, MA 02543, United States. Electronic address: ditplico@usp.br.
authors.forename: D T P
authors.initials: DT
authors.lastname: Lico
authors.affiliation: Department of Cellular & Molecular Biology, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo 14049-900, Brazil; Marine Biological Laboratory, Woods Hole, MA 02543, United States. Electronic address: gabrielsl@usp.br.
authors.forename: G S
authors.initials: GS
authors.lastname: Lopes
authors.affiliation: Department of Cellular & Molecular Biology, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo 14049-900, Brazil; Marine Biological Laboratory, Woods Hole, MA 02543, United States. Electronic address: janabrusco@gmail.com.
authors.forename: J
authors.initials: J
authors.lastname: Brusco
authors.affiliation: Department of Cellular & Molecular Biology, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo 14049-900, Brazil. Electronic address: jcrosa@fmrp.usp.br.
authors.forename: J C
authors.initials: JC
authors.lastname: Rosa
authors.affiliation: Program in Sensory Physiology and Behavior, Marine Biological Laboratory, Woods Hole, MA 02543, United States. Electronic address: rmgould48@gmail.com.
authors.forename: R M
authors.initials: RM
authors.lastname: Gould
authors.affiliation: Biology Department, Providence College, Providence, RI 02918, United States; National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, United States; Marine Biological Laboratory, Woods Hole, MA 02543, United States. Electronic address: joe_degiorgis@hotmail.com.
authors.forename: J A
authors.initials: JA
authors.lastname: De Giorgis
authors.affiliation: Department of Cellular & Molecular Biology, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo 14049-900, Brazil; Marine Biological Laboratory, Woods Hole, MA 02543, United States. Electronic address: relarson@fmrp.usp.br.
authors.forename: R E
authors.initials: RE
authors.lastname: Larson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030541:Databases, Genetic; D049832:Decapodiformes / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013058:Mass Spectrometry; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009899:Optic Lobe, Nonmammalian / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D034441:Heterogeneous-Nuclear Ribonucleoproteins; D011994:Recombinant Proteins
keywords: ELAV; hnRNP; presynaptic terminus; ribonucleoprotein; squid; synaptosome