ABSTRACT
References ........................................................................................................................................ 95
Lipids comprise about 20 to 80% of the mass of a membrane, and therefore, are significant components of membranes. 1·5 Proteins may be inserted into the lipid bilayer (intrinsic proteins) and/or they can be peripherally oriented (extrinsic proteins). The intrinsic proteins can be released by detergent action. In contrast, the extrinsic proteins can be solubilized by either low-ionic strength solutions or treatments, e.g., guanidinium chloride, urea, or dilute acids. Whereas the intrinsic proteins are associated with both lipid leaflets and may traverse the membrane more than once, the peripheral proteins are associated with either the inner or outer leaflet. In addition, transport proteins, i.e., pumps, carriers, and channels, may exist. A discussion of the methods for solubilization of membrane-associated proteins occurs in Zeidan and Dashek.6
