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D-myo-inositol derivatives alter liposomal membrane fluidity
E Brailoiu1, A Margineanu, C P Toma
1Department of Physiology and Biophysics, University of Medicine and Pharmacy Gr. T. Popa Iasi, Romania. brailoiu@umfiasi.ro
Biochemistry and Molecular Biology International
|March 21, 1998
Summary
D-myo-inositol derivatives like IP3 alter membrane fluidity. Lower concentrations of IP4, IP5, and IP6 increase membrane viscosity, suggesting direct roles in biological systems beyond receptor binding.
Area of Science:
- Biochemistry
- Biophysics
- Cell Biology
Background:
- D-myo-inositol derivatives (IP3-IP6) are crucial signaling molecules.
- Their direct impact on cell membrane properties remains incompletely understood.
Purpose of the Study:
- To investigate the effects of inositol phosphates (IP3, IP4, IP5, IP6) on liposome model membrane fluidity.
- To elucidate the direct biophysical mechanisms of inositol derivatives on membranes.
Main Methods:
- Liposome model membranes were prepared and labeled with 1,6-diphenyl-1,3,5 hexatriene (DPH).
- Membrane fluidity was quantified using fluorescence polarization anisotropy.
- The effects of varying concentrations of IP3, IP4, IP5, and IP6 were assessed.
Main Results:
- Inositol trisphosphate (IP3) increased membrane fluidity, with maximal effect at 10(-5) M.
- Inositol tetraphosphate (IP4), IP5, and IP6 reduced fluidity (increased viscosity) at concentrations below 10(-6) M.
- Incorporating IP4, IP5, and IP6 into vesicles enhanced their viscosity-increasing effect.
Conclusions:
- Inositol derivatives directly modulate membrane fluidity and viscosity.
- These direct biophysical interactions may contribute to the biological functions of inositol phosphates.
- This mechanism offers an alternative to receptor-mediated signaling pathways.