Affordable Access

Thermotropic lipid clustering in tetrahymena membranes.

Authors
  • Wunderlich, F
  • Ronai, A
  • Speth, V
  • Seelig, J
  • Blume, A
Type
Published Article
Journal
Biochemistry
Publication Date
Aug 26, 1975
Volume
14
Issue
17
Pages
3730–3735
Identifiers
PMID: 169883
Source
Medline
License
Unknown

Abstract

The effect of temperature on the core structure of endoplasmic reticulum membranes has been visualized directly in cells of the poikilothermic eukaryote Tetrahymena pyriformis by freeze-etch electron microscopy. Moreover, the effect of temperature on the smooth microsomal membrane vesicles isolated from these cells, as well as on the extracted membrane lipids, has been examined by fluorescence probing, electron spin resonance, proton nuclear magnetic resonance, and calorimetry. Freeze-etch electron microscopy of T. pyriformis cells, equilibrated at different temperatures between 28 and 5 degrees, reveals the emergence of smooth areas on the fracture faces of endoplasmic reticulum membranes at temperatures below similar to 17 degrees. In this temperature range, we also find discontinuities in the glucose 6-phosphatase activity, in the fluorescence intensity of 8-anilino-1-naphthalensulfonate, in the partition of 4-doxyldecane, and in the separation of the outer hyperfine extrema of 5-doxylstearic acid in the microsomal membranes. These membranes apparently contain at least two lipid environments of different fluidity as indicated by the 12-doxylstearic acid spin-label. Proton nuclear magnetic resonance of the extracted membrane lipids indicates an abrupt change of the fatty acid chain mobilities at temperatures below similar to 17 degrees. This, however, is not due to a true thermal liquid crystalline in equilibrium crystalline phase transition. Calorimetric measurements also support this conclusion. The thermotropic alterations observed within the membranes are interpreted to be due primarily to a clustering of "rigid" liquid crystalline lipid environments which exclude membrane-intercalating proteins.

Report this publication

Statistics

Seen <100 times