Sequence determinants for hnRNP I protein nuclear localization.
hnRNP I, also referred to as polypyrimidine tract binding protein, is one of the proteins associated with nascent pre-mRNA in the heterogeneous nuclear ribonucleoprotein (hnRNP) complexes. As for all karyophilic proteins, the nuclear import of hnRNP proteins requires specific sequence determinants that in many instances differ from the canonical import signal. In order to identify the sequences responsible for the nuclear localization, various hnRNP I portions were fused to a reporter protein (bacterial chloramphenicol acetyl transferase) and used in transient transfection assay. By this approach we identified a 60-amino-acid sequence located at the amino terminus of hnRNP I (designated NLD-I) that is both necessary and sufficient for nuclear localization. NLD-I represents a novel bipartite type of nuclear localization signal that bears no resemblance to other nuclear localization determinants so far identified in hnRNP proteins.
Romanelli
M G
MG
Istituto di Biologia e Genetica, Strada Le Grazie, 8, Verona, I-37134, Italy. romane@borgoroma.univr.it
Weighardt
F
F
Biamonti
G
G
Riva
S
S
Morandi
C
C
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism*; D015500:Chloramphenicol O-Acetyltransferase; D000242:Cyclic AMP / Q000378:metabolism; D017931:DNA Primers; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D038941:Polypyrimidine Tract-Binding Protein; D011493:Protein Kinase C / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D012261:Ribonucleoproteins / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D017384:Sequence Deletion; D014162:Transfection
D017931:DNA Primers; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D012261:Ribonucleoproteins; D038941:Polypyrimidine Tract-Binding Protein; D000242:Cyclic AMP; D015500:Chloramphenicol O-Acetyltransferase; D011493:Protein Kinase C