Cell Membrane Proteins

Synonyms

Lipid-protein interactions; Transmembrane proteins

Definition

Cellular membranes have a thickness of 7–20 nm and efficiently restrict free passage of nonpolar molecules and cross-membrane communication. To overcome this problem, cells have established a massive membrane protein machinery that regulates most cellular activities ranging from signal transduction to energy balance, respiration, reproduction, and cellular morphology. Thus, the sole existence of multicellular organisms and cells rely on fully functional cell membrane protein system.

Characteristics

A cell and its individual internal compartments are surrounded by a membrane made of lipids. Lipids have a hydrophilic (water loving) and a hydrophobic (water repelling) fatty acid tail (a and b in Fig. 1, respectively). In an aqueous environment, lipids spontaneously self-organize to form lipid bilayers (Fig. 1c) where the hydrophobic parts are shielded from water between the two outer sheets of hydrophilic head groups....