In this study, we analyzed signal transduction by equine follicle-stimulating hormone receptor (eFSHR) on stimulation with recombinant eelFSHβ/α (rec-eelFSHβ/α), natural porcine FSH (pFSH), and natural human FSH (hFSH). cAMP stimulation in CHO-K1 cells expressing eFSHR was determined upon exposure to different doses (0-1450 ng/mL) of these hormones. The EC50 value of rec-eelFSHβ/α was 53.35 ng/mL. The Rmax values of rec-eelFSHβ/α and pFSH were 28.12 and 2.88 ng/mL, respectively. The activity of rec-eelFSHβ/α was much higher than that of natural pFSH. However, signal transduction in CHO PathHunter Parental cells expressing eFSHR was not enhanced by stimulation with natural hFSH. Thus, rec-eelFSHβ/α was completely active in cells expressing eFSHR. However, natural hFSH did not invoke a signal response in cells expressing eFSHR. Particularly, natural pFSH was weakly active in the same cells. These results showed that eelFSHβ/α has potent activity in cells expressing eFSHR. Thus, rec-eelFSHβ/α may efficiently bind to eFSHR, where as natural hFSH does not bind to eFSHR.

ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
  Materials
  Construction of rec-eelFSH
  Production and quantification of rec-eelFSHβ/α proteininCHO suspension cells
  Transient transfection of eFSHR in CHO-K1 cells andstable transfection of eFSHR in PathHunter CHO-K1 EAParentalcells
  Evaluation of cAMP level by homogenous time-resolvedfoster resonance energy transfer (HTRF)
  Data analysis
 RESULTS AND DISCUSSION
 REFERENCES

• Munkhzaya Byambaragchaa(Animal Biotechnology, Graduate School of Future Convergence Technology, Department of Animal Life Science, Institute of Genetic Engineering, Hankyong National University)
• Dae-Jung Kim(Aquaculture Research Division, National Institute of Fisher Science (NIFS))
• Myung-Hwa Kang(Department of Food Science and Nutrition, Hoseo University)
• Kwan-Sik Min(Animal Biotechnology, Graduate School of Future Convergence Technology, Department of Animal Life Science, Institute of Genetic Engineering, Hankyong National University) Corresponding author