CHARACTERIZATION OF THE 5' FLANKING REGION OF THE GENE ENCODING RAT-LIVER GLYCOGEN-PHOSPHORYLASE

A genomic region encompassing 800 bp of the promoter-regulatory region and exon 1 of the gene (LGP) encoding rat liver glycogen phosphorylas e has been isolated and characterized. Transcripts of the LGP gene ini tiate predominantly within an 8-bp region 48-bp upstream from the star t codon. Additional transcripts were detected that initiate as far as 95 bp upstream from the start codon. To identify cis-acting sequences involved in regulating transcription, HepG2 cells were transfected wit h vectors containing serial deletions of the promoter-regulatory regio n of LGP ligated to the cat reporter gene. Two upstream regions were f ound to enhance transcription. One of these regions contains an altern ating purine-pyrimidine sequence. LGP, which lacks a consensus TATA se quence, is like TATA-less and CAAT-less housekeeping genes in that it contains G+C-rich domains upstream from multiple transcription start p oints. Nuclear proteins from adult rat tissues bound in a tissue-speci fic fashion to one of these G+C-rich regions.