On the size and the role of a free cytosolic pool of acidic ribosomal proteins in yeast Saccharomyces cerevisiae.
A small but distinct amount of yeast acidic ribosomal proteins A1/A2 was detected in cytosol by immunoblotting on a two-dimensional gel electrophoretogram, while 38 kDa acidic protein A0 was not detected. The free forms of A1/A2 in the cytosol were eluted in gel filtration at the molecular mass of about 30 kDa under non-denaturation conditions, suggesting that they exist as a dimer or timer without association with A0. The amount of free A1/A2 was determined by immunoblotting to be 0.3% of the ribosome-bound A1/A2 in yeast. The time course of incorporation of radioactive amino acid showed that the cytosolic free A1/A2 are labeled more rapidly with high specific radioactivity than the ribosome-bound A1/A2. This result suggested that some of the cytosolic A1/A2, if not all, are newly-synthesized proteins which are ready for incorporation into cytoplasmic ribosomes.
Mitsui
K
K
Department of Biochemistry, Yamanashi Medical College.
Nakagawa
T
T
Tsurugi
K
K
D003600:Cytosol / Q000378:metabolism; D005656:Fungal Proteins / Q000302:isolation & purification / Q000378:metabolism*; D015151:Immunoblotting; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D008970:Molecular Weight; D012269:Ribosomal Proteins / Q000302:isolation & purification / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
D005656:Fungal Proteins; D012269:Ribosomal Proteins; D007930:Leucine