Requirement for the 3' flanking region of the bovine growth hormone gene for accurate polyadenylylation.

We examined whether the sequence extending 3' to the polyadenylylation site of the bovine growth hormone gene contains any signal that affects the polyadenylylation of the growth hormone mRNA. For this purpose, cloned copies of this gene, each containing a different length of growth hormone-specific sequence 3' to the wild-type polyadenylylation site, were used to transfect COS-1 cells. The polyadenylylation site on the mRNAs produced from the exogenously added growth hormone genes were analyzed with an S1 nuclease mapping procedure. We found that a gene containing 84 base pairs of its own 3' flanking sequence is capable of producing an accurately polyadenylylated mRNA. On the other hand, genes containing only 1, 10, or 13 base pairs of 3' flanking sequence were principally polyadenylylated at discrete sites either upstream or downstream from the wild-type position. Using a computer program, we examined whether secondary structures on the primary growth hormone transcript correlated with the site where the mRNA is polyadenylylated.