Nucleolar targeting of proteins by the tandem array of basic amino acid stretches identified in the RNA polymerase I-associated factor PAF49.
There is accumulating evidence to indicate that the regulation of subnuclear compartmentalization plays important roles in cellular processes. The RNA polymerase I-associated factor PAF49 has been shown to accumulate in the nucleolus in growing cells, but disperse into the nucleoplasm in growth-arrested cells. Serial deletion analysis revealed that amino acids 199-338 were necessary for the nucleolar localization of PAF49. Combinatorial point mutation analysis indicated that the individual basic amino acid stretches (BS) within the central (BS1-4) and the C-terminal (BS5 and 6) regions may cooperatively confer the nucleolar localization of PAF49. Addition of the basic stretches in tandem to a heterologous protein, such as the interferon regulatory factor-3, translocated the tagged protein into the nucleolus, even in the presence of an intrinsic nuclear export sequence. Thus, tandem array of the basic amino acid stretches identified here functions as a dominant nucleolar targeting sequence.
Ushijima
Ryujiro
R
Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki, Nagasaki 852-8523, Japan.
Matsuyama
Toshifumi
T
Nagata
Izumi
I
Yamamoto
Kazuo
K
D000595:Amino Acid Sequence; D024361:Amino Acids, Basic / Q000737:chemistry* / Q000235:genetics; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002466:Cell Nucleolus / Q000378:metabolism*; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D004252:DNA Mutational Analysis; D051379:Mice; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D020449:Repetitive Sequences, Amino Acid; D017384:Sequence Deletion
D024361:Amino Acids, Basic; D002352:Carrier Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; C488429:PAF49 protein, mouse