RIBOSOME, 70S, TERMINATION, RELEASE FACTOR, RF1, STOP CODON, UGA, AMBER, TRNA RECOGNITION OF THE AMBER STOP CODON BY RELEASE FACTOR RF1. THIS ENTRY 3MS1 CONTAINS 50S RIBOSOMAL SUBUNIT. THE 30S RIBOSOMAL SUBUNIT CAN BE FOUND IN PDB ENTRY 3MR8. MOLECULE B IN THE SAME ASYMMETRIC UNIT IS DEPOSITED AS 3MRZ (50S) AND 3MS0 (30S). 3MS1