The behaviors of Ca2+-ATPase embedded in interdigitated bilayer

We investigated the behavior of a membrane protein, Ca2+-ATPase, in interdigitated phospholipid bilayers, The results showed that Ca2+-ATPase does not cause significant alterations in the interdigitation of 16:0 LPC/DPPC (27.0 mol% LPC) vesicles when it is reconstituted with lipids. Intrinsic fluorescence, acrylodan fluorescent adducts, and CD spectra indicated that Ca2+-ATPase, when embedded in interdigitated bilayer structures, is more exposed to the hydrophilic environment and has a looser structure than when embedded in non-interdigitated bilayers, The interdigitation of acyl chains induces a rapid loss of enzyme activity, It is suggested that interdigitated bilayer structures may play an important role as negative regulatory factors in physiological functions.