tokens: A mutation in the 5 ' C2U4 repeat causes underaccumulation of snR13F , whereas mutations in the 3 ' C2U4 repeat cause the accumulation of two novel RNAs that migrate in the 500-nt range .
folded_tokens: a mutation in the 5 ' c2u4 repeat cause underaccumulation of snr13f , whereas mutation in the 3 ' c2u4 repeat cause the accumulation of two novel rna that migrate in the 500-nt range .