Involvement of the Xenopus laevis Ro60 autoantigen in the alternative interaction of La and CNBP proteins with the 5′UTR of L4 ribosomal protein mRNA † 1 †In previous papers the numbering of Xenopus ribosomal proteins followed the system introduced in our first study (Pierandrei-Amaldi & Beccari, 1980). The large amount of sequencing data now accumulated in many species allows adoption of the rat system for a unified nomenclature (Wool et al., 1990). Thus, the Xenopus r-protein that we previously designated L1 is here identified as L4, L14 as L18 and S1 as S3 (Amaldi et al., 1995). 1Edited by M. Yaniv