Abstract
The ribonucleoprotein complex consisting of 5 S RNA and the protein L5 was prepared from the large subunit of rat liver ribosomes. The RNA in the complex was digested in situ with RNase A or RNase T1. The RNase-resistant RNA fragments bound to the protein were recovered and purified by 2 D-PAGE, and their nucleotide sequences were determined in order to elucidate the binding sites of the RNA to the protein.
The results showed that the fragments had arisen from the 5'-end region (residues 1-21), from the second hairpin loop (residues 77-102) and from the 3'-end region (residues 106-120). Harsher digestion trimmed these fragments to shorter fragments. It was concluded that the minimal interactive sequences of 5 S RNA to the protein L5 were residues 13-21, residues 85-102, and residues 106-114. A part of the first hairpin loop, residues 41-52, was also suspected to interact with the protein.
These protein-binding sites of rat liver 5 S RNA were compared with those of Escherichia coli, Halobacterium cutirubrum and yeast, and their probable conservation from eubacteria to eukaryotes is discussed.
