The human 7SL RNA can exist in different conformational states. Sequences involved in conformational changes are homologous to human 5S ribosomal RNA. The first 46 bases at the 5'-end of the 7SL RNA can be shaped into a tRNA-like conformation missing an anticodon stem and loop. From these results a model for the interaction of signal recognition particle with the translating ribosome involving specific RNA sequences is proposed.