Identification of yeast 60 S ribosomal proteins crosslinked to rRNA by 2-iminothiolane

Saccharomyces carlsbergensis 60 S ribosomal subunits were treated with the hetero-bifunctional crosslinking agent 2-iminothiolane and then subjected to mild UV irradiation to introduce protein-rRNA crosslinks. The major crosslinked products were identified as proteins L2, L3, L5, L19 and L23 of which L5 was found to be crosslinked at a 3-5-fold higher efficiency than the other four. Several additional proteins were cross-linked to a detectable but much lower extent.