A series of experiments were conducted to examine the role of Ca2+ in modulating the fluidity of rat small- and large-intestinal antipodal plasma membranes and their liposomes. This bivalent cation was found to decrease the fluidity of these preparations in a complex manner involving at least two distinct mechanisms. The first appeared to be a direct effect of Ca2+ on fluidity, was readily reversible by addition of EGTA and presumably involved binding of Ca2+ to anionic sites in the lipid bilayers of these membranes. This effect was seen with all preparations examined. In contrast, the second effect of Ca2+ on fluidity was only seen in intact small-intestinal brush-border membranes, appeared to be indirect, was time- and cation-dependent, was only minimally reversible by addition of EGTA, and appeared to involve stimulation of membrane-bound enzymes which altered this membrane's fatty acid composition. Furthermore, regional differences in this latter effect of Ca2+ on brush-border membrane fluidity were also seen in these studies, i.e. proximal greater than distal small intestine.
Research Article| November 01 1986
Modulation of lipid fluidity of small- and large-intestinal antipodal membranes by Ca2+
Biochem J (1986) 239 (3): 625–631.
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T A Brasitus, P K Dudeja; Modulation of lipid fluidity of small- and large-intestinal antipodal membranes by Ca2+. Biochem J 1 November 1986; 239 (3): 625–631. doi: https://doi.org/10.1042/bj2390625
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