Structure of rat liver messenger ribo nucleo protein 1. isolation and characterization
Tomcsanyi, T.; Mester, S.; Tigyi, A.
Acta Biochimica et Biophysica Academiae Scientiarum Hungaricae 16(1-2): 11-20
Messenger ribonucleoprotein (mRNP) was released from 0.5 M KCl washed rat liver polyribosomes after mild pancreatic RNase (EC 18.104.22.168) and EDTA treatment and separated by sucrose gradient centrifugation from ribosomal subunits. The method yielded partially fragmented mRNP, which, however, was free from ribosomal contaminants. In CsCl gradient the mRNP banded at 1.46 g/cm3, indicating a protein content of .apprx. 65%. Treatment of mRNP with 0.25 M or 0.5 M KCl resulted in loss of the proteins. Urea/sodium dodecyl sulfate polyacrylamide gel electrophoresis of mRNA bound proteins showed that the most prominent polypeptides in the mRNP fractions exhibited MW of 29,000 (P29), 31,000 (P31), 38,000 (P38), 44,000 (P44), 50,000 (P50), 54,000 (P54), 63,000 (P63), 76,000 (P76) and 105,000 (P150). Three polypeptides, P38, P44 and P63 were most sensitive to high salt treatment.