Size of poly(A)+-mRNA in Saccharomyces cerevisiae polysomes

Abstract The size of poly(A) + -mRNA in different classes of yeast polysomes is estimated. The average molecular weight of long-term labelled polysomal poly(A) + -mRNA is about 0,65 × 10 6 daltons. Approximately 60% of the poly(A) + -mRNA polynucleotide chains located at the 5′ end, are unprotected by ribosomes and degraded by nucleases upon incubation of cell lysates, to yield a population of poly(A) + -mRNA with an average molecular weight of 0,25 × 10 6 daltons.