Complex population of nonpolyadenylated messenger RNA in mouse brain.
The complexity of nonadenylated mRNA [poly(A)-mRNA] has been determined by hybridization with single-copy DNA (scDNA) and cDNA. Our results show that poly(A)- and poly(A)+ mRNA are essentially nonoverlapping (nonhomologous) sequence populations of similar complexity. The sum of the complexities of poly(A)+ mRNA and poly(A)- mRNA is equal to that of total polysomal RNA or total mRNA, or the equivalent of approximately 1.7 x 10(5) different sequences 1.5 kb in length. Poly(A)- mRNA, isolated from polysomal RNA by benzoylated cellulose chromatography, hybridized with 3.6% of the scDNA, corresponding to a complexity of 7.8 x 10(4) different 1.5 kb sequences. The equivalent of only one adenosine tract of approximately 20 nucleotides per 100 poly(A)- mRNA molecules 1.5 kb in size was observed by hybridization with poly(U). cDNA was transcribed from poly(A)- mRNA using random oligonucleotides as primers. Only 1-2% of the single-copy fraction of this cDNA was hybridized using poly(A)+ mRNA as a driver. These results show that poly(A)- mRNA shares few sequences with poly(A)+ mRNA and thus constitutes a separate, complex class of messenger RNA. These measurements preclude the presence of a complex class of bimorphic mRNAs [that is, species present in both poly(A)+ and poly(A)- forms] in brain polysomes.
D000818:Animals; D001483:Base Sequence; D001923:Brain Chemistry; D004247:DNA; D051379:Mice; D009693:Nucleic Acid Hybridization; D011061:Poly A / Q000032:analysis; D011132:Polyribosomes / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis*
D012333:RNA, Messenger; D011061:Poly A; D004247:DNA