Abstract
Neither of the 2 previously proposed secondary structures for eukaryotic 5.8S RNA is consistent with the present laser Raman results [obtained for Saccharomyces cerevisiae]. A new, highly stable cloverleaf secondary structure not only fits the Raman data but also accounts for previously determined enzymatic partial cleavage patterns, base sequence and pairing homologies, and G.cntdot.C and A.cntdot.U base pair numbers and ratios. The new cloverleaf model also conserves several structural features (constant loops, bulges and stems) consistent with known 5.8S RNA functions. A similar new cloverleaf secondary structure for Escherichia coli 5S RNA is proposed, consonant with many known properties of prokaryotic 5S RNA.