Considering formation of biomembranes and its function from a viewpoint of physical property of lipids.

The interactions of membrane proteins with lipid bilayers are principally hydrophobic and electrostatic in nature. Integral proteins interact hydrophobically with the hydrocarbon chains of membrane lipids by crossing the bilayer once or several times. Since every biomembrane contains a wide variety of different lipid species, an understanding of the differential interactions between proteins and lipids is required to clarify many aspects of membrane functions. The integral membrane proteins have an amphipathic nature since there exist separated surfaces of hydrophobic and hydrophilic regions. The hydrophobic force is the major factor in constructing the biomembrane structures, and so the hydrophobic part of integral protein traverses or penetrates the hydrophobic core of the lipid bilayer. In this review, matching of the hydrophobic regions of the lipids and proteins in membranes is discussed, and then a possible mechanism of activating protein kinase C in signal transduction of phosphatidylinositol cycle.