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Binding Sites for IGF-I Identified on Theca Cells from Large Porcine Follicles

  • Brigitte Caubo
  • Sharon A. Tonetta

Abstract

Theca from large porcine follicles (>8mm) were examined for specific IGF-I binding sites. Thecal membranes were prepared and then incubated overnight at 4°C with I-IGF-I with or without increasing concentrations of IGF-I, IGF-II and insulin. Specific high-affinity IGF-I binding sites were demonstrated. Scatchard analysis gave a curvilinear plot with a Ka for the high affinity sites of 1.97 ± 0.35 nM (binding capacity, 305.7±37.2 fmol/mg protein). Preferential binding was IGF-I>IGF-II>insulin. Interestingly, IGFs modulate steroidogenesis in porcine theca cells with a similar order of potency. These data demonstrate high affinity, low capacity binding of IGF-I to porcine thecal membranes and suggest that IGF-I and related peptides act on thecal steroidogenesis through IGF-I receptors.

Keywords

Granulosa Cell Follicular Fluid Theca Cell Scatchard Analysis Acanthosis Nigricans 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Plenum Press, New York 1989

Authors and Affiliations

  • Brigitte Caubo
    • 1
  • Sharon A. Tonetta
    • 1
  1. 1.Livingston Reproductive Biology Lab, Medical CenterUniversity of Southern CaliforniaLos AngelesUSA

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