Variability of polyadenylation sites in mRNAs from human fetal liver.

cDNA libraries of human fetal liver were constructed in pBR322 and lambda gt10 vectors. The libraries were screened for liver-specific clones by differential hybridization. This procedure revealed 25 and 32 liver-specific clones in plasmid and phage libraries, respectively. The majority of these clones were represented with serum albumin, fetal G gamma-globin and A gamma-globin cDNA inserts. Three types of 3'-non-coding region were found in 5 sequenced albumin cDNAs. In one type mRNA the distance between the AATAAA signal and polyadenylation site was 15 nucleotides, in 2 other types this distance was 10 and 6 nucleotides. The polyadenylation site in the G gamma-globin cDNA was located 2 nucleotides further from AATAAA signal, while in the A gamma-globin cDNA it was 2 nucleotides closer to the signal as compared with the results published previously.