title: A novel role for the nuclear localization signal in regulating hnRNP K protein stability in vivo.
abstract: hnRNP K is a highly conserved nucleocytoplasmic shuttling protein, which associates with RNAs through synergistic binding via its three KH domains. hnRNP K is required for proper nuclear export and translational control of its mRNA targets, and these processes are controlled by hnRNP K's movement between subcellular compartments. Whereas the nuclear export and localization of hnRNP K that is associated with mRNP complexes has been well studied, the trafficking of hnRNP K that is unbound to mRNA has yet to be elucidated. To that end, we expressed an EGFP-tagged RNA binding-defective form of hnRNP K in intact Xenopus embryos, and found it was rapidly degraded in vivo. Deleting hnRNP K's nuclear localization signal (NLS), which contains two prospective ubiquitination sites, rescued the protein from degradation. These data demonstrate a novel activity for the NLS of hnRNP K in regulating the protein's stability in vivo when it is unbound to nucleic acids.
authors: Department of Biological Sciences and Center for Neuroscience Research, University at Albany, State University of New York, Albany, NY 12222, USA.
authors: Erica J
authors: EJ
authors: Hutchins
authors: Department of Biological Sciences and Center for Neuroscience Research, University at Albany, State University of New York, Albany, NY 12222, USA.
authors: Jamie L
authors: JL
authors: Belrose
authors: Department of Biological Sciences and Center for Neuroscience Research, University at Albany, State University of New York, Albany, NY 12222, USA. Electronic address: bgs86@albany.edu.
authors: Ben G
authors: BG
authors: Szaro
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D004625:Embryo, Nonmammalian; D015870:Gene Expression; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000235:genetics* / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D019913:Nuclear Localization Signals / Q000235:genetics* / Q000378:metabolism; D000072417:Protein Domains; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D055550:Protein Stability; D059748:Proteolysis; D011993:Recombinant Fusion Proteins / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D054875:Ubiquitination; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics* / Q000378:metabolism
chemical_list: D034441:Heterogeneous-Nuclear Ribonucleoproteins; D019913:Nuclear Localization Signals; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins
keywords: KH domain; Nuclear localization signal; RNA-binding protein; Xenopus; hnRNP K