The Isolation and Characterization of Adenosine Monophosphate-rich Polynucleotides Synthesized by Soybean Hypocotyl Cells

Plant ribonucleic acids which have high adenosine monophosphate concentrations were studied. Purified deoxyribonucleic acid-like ribonucleic acid and tenaciously bound ribonucleic acid fractions both contained poly-adenosine monophosphate sequences (those from the latter being longer than those from the former); without these poly-adenosine monophosphate sequences their base compositions were the same. The average poly-adenosine monophosphate sequence from purified tenaciously bound ribonucleic acid was 160 residues long, as measured by gel electrophoresis. However, base hydrolysis and chromatography indicated one 3'-nucleoside (adenosine) per 71 nucleotides, giving a chain length of 72 residues. The dominant species in the cytoplasm, as measured by radioactive precursor incorporation, was tenaciously bound ribonucleic acid, whereas deoxyribonucleic acid-like ribonucleic acid was present in greater amounts in the nucleus. This work provides evidence that deoxyribonucleic acid-like ribonucleic acid and tenaciously bound ribonucleic acid represent forms of messenger ribonucleic acid in soybean, with deoxyribonucleic acid-like ribonucleic acid residing in the nucleus, perhaps as the messenger ribonucleic acid precursor, and tenaciously bound ribonucleic acid residing, as the active messenger ribonucleic acid, in the cytoplasm.