ABSTRACT
Prostacyclin-stimulating factor (PSF) is a protein which acts on vascular endothelial cells and stimulates the production of prostacyclin. Recently, we were able to purify PSF from the conditioned medium of cultured human diploid fibroblasts and clone PSF cDNA. In this study, we screened a human genomic library and isolated genomic clones to determine the structure of the human chromosomal PSF gene. By determining the nucleotide sequence and transcription initiation site of this gene, we found that it comprises 5 exons and 4 introns. Southern hybridization analysis indicated the presence of a single copy of the PSF gene per haploid set of chromosomes. The 300 bp upstream of the transcription initiation site had a very high GC content, and 7 binding sites for the transcription regulating factor Sp1 were present.