Exp Clin Endocrinol Diabetes 2002; 110(2): 77-79
DOI: 10.1055/s-2002-23490
Articles

© Johann Ambrosius Barth

Thermal destabilization of ovarian LH/hCG receptors by negatively charged lipids

J. Kolena, S. Scsuková, M. Ježová
  • Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic
Weitere Informationen

Publikationsverlauf

received 08 August 2000 first decision 10 November 2000

accepted 26 September 2001

Publikationsdatum:
27. März 2002 (online)

Summary

The stabilizing effect of BSA on the rat ovarian LH/hCG receptor was analyzed by thermal perturbation technique. Thermal destabilization of the receptor with arachidonic acid along with digestion of membrane with phospholipase A2 and reversal of these effects when BSA was used as fatty acids scavenger, may indicate that free fatty acids are responsible for instability of the LH/hCG receptor. This destabilizing effect may be caused by the presence of a net negative surface charge provided by fatty acids. This presumption was corroborated by the reconstitution of delipidated LH/hCG receptor into proteoliposomes. Delipidated receptor lost to a great extent its binding activity and thermal stability. The receptor was fully reactivated by the reconstitution into proteoliposomes with neutral phosphatidylcholine but not with negatively charged phosphatidylserine and phosphatidylglycerol. Thermal inactivation of the LH/hCG receptor by delipidation was entirely inverted by treatment with phosphatidylcholine but the presence of negatively charged phospholipids did not change the heat inactivation profile of hCG-binding sites.

References

  • 1 Arakawa T, Timasheff S N. The stabilization of proteins by osmolytes.  Biophys J. 1985;  47 411-414
  • 2 Artigues A, Villar M T, Fernandez A M, Ferragut J A, Gonzales-Ross J M. Cholesterol stabilizes the structure of the nicotinic acetylcholine receptor reconstituted in lipid vesicles.  Biochim Biophys Acta. 1989;  985 325-330
  • 3 Kolena J. Functional reconstitution of rat ovarian LH/hCG receptor into proteoliposomes.  FEBS Lett. 1989;  250 425-428
  • 4 Kolena J, Blažíček P, Horkovics-Kováts Š, Ondriáš K, Šeboková E. Modulation of rat testicular LH/hCG receptors by membrane lipid fluidity.  Mol Cell Endocrinol. 1986;  44 69-76
  • 5 Kolena J, Ježová M, Vranová J, Scsuková S. Structure-stabilizing effect of albumin on rat ovarian LH/hCG receptors.  Biochem Biophys Acta. 1999;  1416 208-216
  • 6 Kolena J, Matejčíková K, Šrenkelová G. Osmolytes improve the reconstitution of luteinizing hormone/human chorionic gonadotropin receptors into proteoliposomes.  Mol Cell Endocrinol. 1992;  83 201-209
  • 7 Kolena J, Scsuková S, Tatara M, Jasem P. Effect of partial delipidation of rat ovarian membranes on thermal stability of LH/hCG receptors.  Biochim Biophys Acta. 1994;  1193 293-300
  • 8 Lewitzki A. Reconstitution of membrane receptor systems.  Biochim Biophys Acta. 1985;  822 127-153
  • 9 Lowry O H, Rosenbrough N J, Farr A L, Randall R J. Protein measurement with the Folin phenol reagent.  J Biol Chem. 1951;  193 265-275
  • 10 Metsikko M K, Petaja-Repo U E, Lakkakorpi J T, Rajaniemi H J. Structural features of the LH/CG receptor.  Acta Endocrinol. 1990;  122 545-552
  • 11 Segaloff D L, Ascoli M. The lutropin/choriogonadotropin receptor ‥ 4 years later.  Endocrine Rev. 1993;  14 324-347
  • 12 Straubinger R M, Duzgunes N, Papahadjopoulos D. pH-sensitive liposomes mediate cytoplasmatic delivery of encapsulated macromolecules.  FEBS Lett. 1985;  179 148-154

Jaroslav Kolena

Institute of Experimental Endocrinology

Slovak Academy of Sciences

Vlarska 3

83306 Bratislava

Slovak Republic

Fax: +4217 54772800

eMail: ueenkole@savba.savba.sk