ABSTRACT
The lumenal and contralumenal plasma membranes of the rat enterocyte, the predominant cell type lining the small intestine, are highly differentiated to perform a variety of digestive and transport functions. The functional interaction between proteins and lipids of these membranes has been examined using steady-state fluorescence polarization and differential scanning calorimetry (DSC). In 1977, D. Schachter and M. Shinitzky" first demonstrated that rat microvillus membrane possessed a relatively low lipid fluidity, as determined by fluorescence polarization studies, utilizing the fluorophor 1,6-diphenyl-1,3,5,-hexatriene (DPH). In Escherichia coli and Mycoplasma membranes, with well-defined lipid thermotrophic transitions, it has been shown that a temperature-dependent change in the physical state of the lipid influenced certain membrane activities dependent on proteins, transmembrane transport mechanisms. Rat enterocyte basolateral membrane lipid has also been shown to undergo a broad reversible thermotrophic phase transition between 27 to 40°C as assessed by DSC studies.
