INTRONIC POLYADENYLATION IN THE HUMAN GLYCINAMIDE RIBONUCLEOTIDE FORMYLTRANSFERASE GENE

The mouse glycinamide ribonucleotide formyltransferase (CART) locus is known to produce two functional proteins, one by recognition and use of an intronic polyadenylation site and the other by downstream splici ng. We now report a similar intronic polyadenylation mechanism for the human CART locus, The human CART gene has two potential polyadenylati on signals within the identically located intron as that involved in i ntronic polyadenylation in the mouse gene. Each of the potential polya denylation signals in the human gene was followed by an extensive poly T rich tract, but only the downstream signal was preceded by a GT trac t, Only the downstream signal was utilized, The poIyT rich tract which followed the functional polyadenylation site in the human GART gene w as virtually identical in sequence to a similarly placed region in the mouse gene. An exact inverted complement to the poIyT rich stretch fo llowing the active polyadenylation signal was found in the upstream in tron of the human gene, suggesting that a hairpin loop may be involved in this intronic polyadenylation.