Prostaglandin E1 binds to Z protein of rat liver.
Z protein or fatty-acid-binding protein is abundant in the cytosol of many cell types including liver cells. It is considered to play an important role in intracellular transport and metabolism of long-chain fatty acids and other organic anions. We studied the role of Z protein in the metabolism of prostaglandin E1 (PGE1). Binding of tritiated prostaglandin E1 to this fatty-acid-binding protein (Z protein) purified from rat liver was determined. The binding of [3H]prostaglandin E1 to Z protein is rapid, saturable and reversible. Scatchard analysis of [3H]PGE1 binding to Z protein showed a single class of binding sites with a dissociation constant (Kd) of 37 nM. The binding capacity is 110 nmol/mg Z protein. Optimal [3H]PGE1 binding occurred at pH 7.4. The presence of 3 mM MgCl2 stimulated the prostaglandin E1 binding to Z protein. Competition experiments show that the binding of this autacoid to Z protein is highly specific. It could not be displaced by other prostaglandins (PGA1, PGA2, PGE2, PGB1, PGI2, PGD2, PGF2 alpha, and 6-keto PGF1 alpha). Z protein might be involved in the metabolism of prostaglandins in the cytosol.
D000527:Alprostadil / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism* / Q000502:physiology; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D011919:Rats, Inbred Strains
D002352:Carrier Proteins; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D000527:Alprostadil