J. Meyerkirchrath et al., ANALYSIS OF A PORCINE EP3-RECEPTOR - CLONING, EXPRESSION AND SIGNAL-TRANSDUCTION, Naunyn-Schmiedeberg's archives of pharmacology, 358(2), 1998, pp. 160-167
A cDNA clone, encoding a complete porcine EP3 receptor, was isolated f
rom a porcine heart cDNA library. The deduced amino acid sequence reve
aled a protein of 387 amino acid residues with an estimated molecular
weight of 43 kD and strongest homology to the human EP3-II receptor (8
4% identity on protein level). Ligand binding studies with transfected
COS-7 cells, expressing the porcine receptor. showed displacement of
[H-3]PGE(1) with the EP3-specific agonist M&B 28.767, the EP1/EP3-agon
ist sulprostone but not with the EP2-specific agonist butaprost. Stimu
lation of transfected CHO cells with M&B 28.767 resulted in inhibition
of forskolin-induced cAMP formation, suggesting coupling to an inhibi
tory G protein. Agonist-induced translocation of the transcription fac
tor NF kappa B into the nucleus of transfected CHO cells was demonstra
ted by Western blot analysis, indicating that these EP3 receptors modu
late NF kappa B-dependent cellular signal transduction. Analysis of th
e genomic organization identified the major transcription initiation s
ite at about 160 bp upstream of the ATG start codon. The 800-bp 5' fla
nking region contains a variety of putative fis-acting regulatory elem
ents, including binding sites for AP2, SP1 and MyoD (E-box). The prese
nt data will now allow further studies on EP3 receptor-mediated signal
transduction and its regulation.