The subcellular distribution of the human ribosomal "stalk" components: P1, P2 and P0 proteins.
The ribosomal "stalk" structure is a distinct lateral protuberance located on the large ribosomal subunit in prokaryotic, as well as in eukaryotic cells. In eukaryotes, this ribosomal structure is composed of the acidic ribosomal P proteins, forming two hetero-dimers (P1/P2) attached to the ribosome through the P0 protein. The "stalk" is essential for the ribosome activity, taking part in the interaction with elongation factors. In this report, we have shown that the subcellular distribution of the human P proteins does not fall into standard behavior of regular ribosomal proteins. We have used two approaches to assess the distribution of the P proteins, in vivo experiments with GFP fusion proteins and in vitro one with anti-P protein antibodies. In contrast to standard r-proteins, the P1 and P2 proteins are not actively transported into the nucleus compartment, remaining predominantly in the cytoplasm (the perinuclear compartment). The P0 protein was found in the cytoplasm, as well as in the nucleus; however, the nucleoli were excluded. This protein was scattered around the nuclei, and the distribution might reflect association with the so-called nuclear bodies. This is the first example of r-proteins that are not actively transported into the nucleus; moreover, this might imply that the "stalk" constituents are assembled onto the ribosomal particle at the very last step of ribosomal maturation, which takes part in the cell cytoplasm.
Tchórzewski
Marek
M
Department of Molecular Biology, Institute of Microbiology and Biotechnology, Maria Curie-Sklodowska University, Akademicka Street 19, 20-033, Lublin, Poland.
Krokowski
Dawid
D
Rzeski
Wojciech
W
Issinger
Olaf-Georg
OG
Grankowski
Nikodem
N
D016475:3T3 Cells; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D013347:Subcellular Fractions
D008164:Luminescent Proteins; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; D012269:Ribosomal Proteins; C031937:phosphoprotein P2, ribosomal; C035690:ribosomal phosphoprotein P1; C054675:ribosomal protein P0; D049452:Green Fluorescent Proteins