Export of ribosomal subunits from resealed rat liver nuclear envelopes.
We have previously described the rat liver resealed nuclear envelope model system for the study of the selective import of nuclear proteins, and the export of poly(A)-containing mRNA [Riedel, N., Bachmann, M., Richter, H. & Fasold, H. (1987) Proc. Natl Acad. Sci. USA 83, 3540-3544]. The vesicles still respond to the importin-ATP signal for the uptake of nuclear-location-sequence (NLS)-carrying proteins. During the preparation of the vesicles and extraction of the chromatin from nuclei in cold hypotonic heparin solution, ribosomal subunits may be introduced into these envelopes, and after resealing remain stably included. Efflux from the resealed nuclear envelopes is effected by a cytoplasmatic protein fraction, and strongly enhanced in the presence of ATP. The heterogeneous nuclear RNP (hnRNP) A1, the components of importin, or GTP showed no influence on this export. The ATP-dependent efflux of mRNA is not affected by these cytoplasmic proteins in this model system.
Institut für Biochemie der Johann Wolfgang Goethe-Universität Frankfurt, Germany.
I
I
Hassel
V
V
Cézanne
C
C
Treviño
H
H
Schlatter
I
I
Romero-Matuschek
A
A
Schmidt
H
H
Fasold
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D004591:Electrophoresis, Polyacrylamide Gel; D016650:Fluorescein-5-isothiocyanate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000494:pharmacology; D007150:Immunohistochemistry; D028884:Karyopherins; D008099:Liver / Q000378:metabolism; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D056489:Nucleoplasmins; D010750:Phosphoproteins; D012333:RNA, Messenger / Q000378:metabolism; D015138:RNA, Nuclear / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism*; D051381:Rats; D012269:Ribosomal Proteins / Q000378:metabolism; D020931:ran GTP-Binding Protein
D028884:Karyopherins; D009687:Nuclear Proteins; D056489:Nucleoplasmins; D010750:Phosphoproteins; D012333:RNA, Messenger; D015138:RNA, Nuclear; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D020931:ran GTP-Binding Protein; D016650:Fluorescein-5-isothiocyanate