Human tRNA^Sec associates with HeLa membranes, cell lipid liposomes, and synthetic lipid bilayers

Enrichment of tRNA^Sec in membrane fractions as measured by the double-probe Northern. (A) Specific concentration of tRNA^Sec in the sucrose fractions 3s, 8s, and 12s containing HeLa cell membranes. The broken line represents the specific concentration of tRNA^Sec in fraction C, applied to the sucrose gradient for the fractionation. (B) Affinity of tRNA^Sec for liposomes (“lipos”) composed of lipids extracted from HeLa cell membranes. RNA was separately extracted from HeLa cells (“total RNA”) and from sucrose gradient fractions (“fract”) 3s, 8s, and 12s. The ordinate (specific concentration of tRNA^Sec) represents the mass of tRNA^Sec under the liposomal region divided by the mass of all RNAs under the liposomal region. Bars are the standard error of the mean (three experiments).