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Updated: Sep 29, 2026

Collection of Human Follicular Fluid, Follicle Somatic Cells, and Immature Oocytes from Individuals Undergoing In Vitro Fertilization
Published on: October 24, 2025
A 60-66 kDa protein with gonadotrophin surge attenuating factor bioactivity is produced by human ovarian granulosa
Paul A Fowler1, Tarja Sorsa-Leslie, Phillip Cash
1Department of Obstetrics and Gynaecology, University of Aberdeen, Aberdeen, AB25 2ZD, UK. p.a.fowler@abdn.ac.uk
Abstract:
We aimed to confirm the ovarian site of gonadotrophin surge-attenuating factor (GnSAF) production and produce granulosa/luteal cell-conditioned medium (G/LCM) containing GnSAF for purification studies. Blue dye affinity chromatography followed by pseudochromatofocusing of G/LCM yielded bioactive fractions at pH 5.74 and 5.77. The former had a major 60-66 kDa band with an internal amino acid sequence of EPQVYVHAP following tryptic digestion. A rat polyclonal antiserum (rPAb) raised against this band completely blocked in-vitro GnSAF bioactivity in human follicular fluid, serum and G/LCM. GnSAF bioactivity was localized to a 64 kDa band of serum-free G/LCM and following 2D gel electrophoresis, one of the spots recognized by Western blotting with the GnSAF rPAb had an N-terminal amino acid sequence of NH-XVPQGNAXXN. Neither amino acid sequence had significant homology with proteins in the human genome database. When ovarian tissues from spontaneously cycling women were cultured under serum-free conditions, neither theca- nor stroma-conditioned media contained GnSAF bioactivity. However, granulosa cell-conditioned medium significantly reduced GnRH-induced LH secretion, an effect that was reversed by incubation with the GnSAF rPAb. In conclusion, we have confirmed that human granulosa cells produce GnSAF within the ovary and have two candidate amino acid sequences for GnSAF. We have also demonstrated that serum-free granulosa cell culture constitutes the method of choice for the characterization of GnSAF since recovery of bioactivity is superior in the presence of fewer serum proteins.
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