Purification and partial sequencing of high-affinity progesterone-binding site(s) from porcine liver membranes

Eur J Biochem. 1996 Aug 1;239(3):726-31. doi: 10.1111/j.1432-1033.1996.0726u.x.

Abstract

High-affinity progesterone-binding sites have been identified, characterized in and purified from porcine liver membranes. They were functionally solubilized by the non-denaturing zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (Chaps, 20 mM. detergent/protein mass ratio 4:1) at a yield of 75-80%. Using [3H]progesterone as radioligand, binding studies showed high-affinity and low-affinity binding sites in microsomal preparations with an apparent Kd2 of 11 nM and an apparent Kd2 of 286 nM. In solubilized fractions the high-affinity binding sites were present at an apparent Kd2 of 69 nM. In both preparations, progesterone binding was time-dependent, saturable, reversible, and showed a similar hierachy of affinities for related steroids. A purification scheme was developed based on anion-exchanger procedures. The purified fraction as identified by maximum specific progester-one-binding activity contained two major polypeptides of apparent molecular masses (SDS/PAGE) of 28 kDa and 56 kDa, respectively. Sequencing of both polypeptides showed an identical amino terminus without significant identity in the amino acid sequence to any known protein primary structure.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Microsomes, Liver / chemistry*
  • Microsomes, Liver / metabolism
  • Molecular Sequence Data
  • Progesterone / metabolism*
  • Receptors, Progesterone / isolation & purification*
  • Receptors, Progesterone / metabolism
  • Sequence Analysis
  • Solubility
  • Swine

Substances

  • Receptors, Progesterone
  • Progesterone