They constitute a layer, or an annulus/ shell, of lipids which are partially immobilized due to the existence of lipid-protein interactions.
However, they may be slightly restricted in their segmental motion freedom due to mild peer pressure of protein molecules, if present in high concentration, which arises from extended influence of protein-lipid interaction.
Membrane areas away from protein molecules contain lamellar phase bulk lipids, which are largely free from any restraining effects due to protein-lipid interactions.
This phenomenon can be studied by the spin label electron paramagnetic resonance technique.
The protein-lipid binding are dependent[1] on OmpF pH levels and their structural features and location of the membranes.