The use of 2-iminothiolane as an RNA-protein cross-linking agent in Escherichia coli ribosomes, and the localisation on 23S RNA of sites cross-linked to proteins L4, L6, L21, L23, L27 and L29.

When E. coli ribosomal subunits are reacted with 2-iminothiolane and then subjected to a mild ultraviolet irradiation, an RNA-protein cross-linking reaction occurs. About 5% of the total protein in each subunit becomes cross-linked to the RNA, and a specific sub-set of proteins is involved in the reaction. In the case of the 50S subunit, the sites of cross-linking to the 23S RNA have been determined for six of these proteins: protein L4 is cross-linked within an oligonucleotide comprising positions 613-617 in the 23S sequence, L6 within positions 2473-2481, L21 within positions 540-548, L23 within positions 137-141, L27 within positions 2332-2337 and L29 within positions 99-107.