Cell density-dependent nuclear/cytoplasmic localization of NORPEG (RAI14) protein

Biochem Biophys Res Commun. 2006 Jul 14;345(4):1333-41. doi: 10.1016/j.bbrc.2006.04.184. Epub 2006 May 16.


NORPEG (RAI14), a developmentally regulated gene induced by retinoic acid, encodes a 980 amino acid (aa) residue protein containing six ankyrin repeats and a long coiled-coil domain [Kutty et al., J. Biol. Chem. 276 (2001), pp. 2831-2840]. We have expressed aa residues 1-287 of NORPEG and used the recombinant protein to produce an anti-NORPEG polyclonal antibody. Confocal immunofluorescence analysis showed that the subcellular localization of NORPEG in retinal pigment epithelial (ARPE-19) cells varies with cell density, with predominantly nuclear localization in nonconfluent cells, but a cytoplasmic localization, reminiscent of cytoskeleton, in confluent cultures. Interestingly, an evolutionarily conserved putative monopartite nuclear localization signal (P(270)KKRKAP(276)) was identified by analyzing the sequences of NORPEG and its orthologs. GFP-NORPEG (2-287 aa), a fusion protein containing this signal, was indeed localized to nuclei when expressed in ARPE-19 or COS-7 cells. Deletion and mutation analysis indicated that the identified nuclear localization sequence is indispensable for nuclear targeting.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies / immunology
  • Blotting, Western
  • COS Cells
  • Cell Count
  • Cell Line
  • Cell Nucleolus / metabolism
  • Cell Nucleus / metabolism*
  • Chlorocebus aethiops
  • Cytoplasm / metabolism*
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / immunology
  • Cytoskeletal Proteins / metabolism*
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Histidine / genetics
  • Humans
  • Microscopy, Confocal
  • Molecular Sequence Data
  • Mutation
  • Nuclear Localization Signals / genetics
  • Peptide Fragments / genetics
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Deletion
  • Sequence Homology, Amino Acid
  • Transcription Factors / genetics
  • Transcription Factors / immunology
  • Transcription Factors / metabolism*
  • Transfection


  • Antibodies
  • Cytoskeletal Proteins
  • Nuclear Localization Signals
  • Peptide Fragments
  • RAI14 protein, human
  • Recombinant Fusion Proteins
  • Transcription Factors
  • Green Fluorescent Proteins
  • Histidine