Macroscopic domain formation during cooling in the platelet plasma membrane: an issue of low cholesterol content.

R.BALI; L. SAVINO; D.A. RAMIREZ; N.M TSVETKOVA; LUIS A. BAGATOLLI; F. TABLIN; J.H. CROWE; C. LEIDY

BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2009 vol. 1788 p. 1229 - 1229

0005-2736

here has been ample debate on whether cell membranes can present macroscopic lipid domains as predicted by three-component phase diagrams obtained by fluorescence microscopy. Several groups have argued that membrane proteins and interactions with the cytoskeleton inhibit the formation of large domains. In contrast, some polarizable cells do show large regions with qualitative differences in lipid fluidity. It is important to ask more precisely, based on the current phase diagrams, under what conditions would large domains be expected to form in cells. In this work we study the thermotropic phase behavior of the platelet plasma membrane by FTIR, and compare it to a POPC/Sphingomyelin/Cholesterol model representing the outer leaflet composition. We find that this model closely reflects the platelet phase behavior. Previous work has shown that the platelet plasma membrane presents inhomogeneous distribution of DiI18:0 at 24°C, but not at 37°C, which suggests the formation of macroscopic