Specific binding of [3H]17α,20β-dihydroxy-4-pregnen-3-one to oocyte cortices of rainbow trout (Oncorhynchus mykiss)

Michiyasu Yoshikuni, Naoki Shibata, Yoshitaka Nagahama

Research output: Contribution to journalArticlepeer-review

57 Citations (Scopus)


Specific binding of [3H]17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP) to plasma membranes prepared from defolliculated oocytes of rainbow trout (Onchorhynchus mykiss) was identified and characterized. Binding was rapid and reached equilibrium in 30 min. 17α,20β-DP strongly inhibited [3H] 17α,20β-DP binding in a competitive manner. Scatchard analysis revealed two different binding sites: a high affinity binding site with a Kd of 18 nM and a Bmax of 0.2 pmoles/mg protein; and a low affinity binding site with a Kd of 0.5 μM and a Bmax of 1 pmoles/mg protein. This binding activity was successfully solubilized with n-heptyl-β-D-thioglucoside. [3H]17α,20β-DP binding to solubilized preparations reached equilibrium in 1h, and was competitively inhibited with 17α,20β-DP and 17α,20β,21-trihydroxy-4-pregnen-3-one. However, Scatchard analysis showed a single binding site with a Kd of 0.3 μM. The reason for the disappearance of the high affinity binding site in solubilized preparations remains unclear. These results demonstrate that a specific binding site for 17α,20β-DP exists in the plasma membrane of rainbow trout oocytes.

Original languageEnglish
Pages (from-to)15-24
Number of pages10
JournalFish Physiology and Biochemistry
Issue number1-6
Publication statusPublished - Jul 1993
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physiology
  • Biochemistry
  • Aquatic Science


Dive into the research topics of 'Specific binding of [3H]17α,20β-dihydroxy-4-pregnen-3-one to oocyte cortices of rainbow trout (Oncorhynchus mykiss)'. Together they form a unique fingerprint.

Cite this