Structure and expression of the human gene encoding plasminogen activator inhibitor, PAI-1

The gene (pai1) encoding human plasminogen activator inhibitor, PAI-1 was cloned from a lambda EMBL3 genomic library and was found to span approx. 12 kb and to contain eight introns. Primer extension and S1 nuclease analyses both showed the transcription start point to be located 142 nt upstream from the start codon. The 5'-flanking region was sequenced and found to contain a TATA box, but no CAAT sequence. When a fragment containing 730 nt of 5'-untranslated region was placed upstream from a promoterless cat gene, it was shown to function as a promoter when transfected into COS cells. Northern-blot analysis was consistent with low level expression of the endogenous pai1 gene in COS cells. When the pai1 gene structure was compared to those of other members of the serine-protease-inhibitor encoding gene family, little conservation of intron positions was observed.