Cell Membrane Features

Philip L Yeagle, Rutgers University, Newark, New Jersey, USA

Published online: December 2009

DOI: 10.1002/9780470015902.a0001261.pub2

The membranes of living cells support much of the functionality of biology. From the subcellular level of organelles to the supercellular level of cell–cell interactions, membranes provide the structures necessary for biological function and organization. Many of those structural and functional features are common among membranes in bacteria, eukaryotic cells and viruses. The lipid bilayer provides the fundamental architecture and some of the properties common to all biological membranes. Membrane proteins confer a myriad of specific functions expressed by cell membranes. Plasma membranes determine the boundary of the cell and many of the interactions of the cell with its environment. Intracellular membranes compartmentalize cells into different functional units with differing internal compositions. The composition of the compartments is maintained by essential transport functions in concert with permeability control. Signal transduction is supported by membranes. Membrane fusion provides a mechanism for intracellular vesicular transport and enveloped virus entry into cells.

Key concepts:

  • The hydrophobic effect, which governs the behaviour of hydrocarbons in water, controls the structures formed by membrane lipids and membrane proteins.
  • Many properties of membranes are conferred by fundamental properties of lipid bilayers that form the basic structure for all biological membranes.
  • Transmembrane proteins have different organizations of amino acids in their primary sequence such that linear sequences of amino acids are available to transit the lipid bilayer.
  • Integral membrane proteins have a portion of their mass buried in the lipid bilayer.
  • Peripheral membrane proteins are much like soluble proteins in structure, but are bound to membranes.
  • Much cellular function is conferred by cell membranes, including compartmentalization, transport, enzyme activity, intracellular trafficking, enveloped viral entry, signal transduction, endocytosis, phagocytosis, action potentials and RNA processing, to name a few.
  • Specialized cell membranes have specialized functions for cells.

Keywords: membrane protein; lipid bilayer; membrane transport; signal transduction; membrane fusion; plasma membrane

Figure 1. Schematic representation of a lipid bilayer. The circles represent the polar headgroups of the lipids, and the lines connected to the circle represent the hydrophobic hydrocarbon chains of the lipids. These amphipathic molecules are dual nature: one end is hydrophilic and the other end is hydrophobic. They organize so as to limit the exposure of the hydrophobic portions to the aqueous phase that is found on both sides of the membrane.
Figure 2. Schematic representation of the incorporation of a transmembrane protein into a lipid bilayer. The cylinders represent hydrophobic transmembrane helices, the dark lines are loops of the polypeptide chain that connect the helices, and the lipids are represented as in Figure 1.
Figure 3. Schematic representation of the classes of membrane proteins. The darker shaded regions are the hydrophobic portions of these membrane proteins and the clear horizontal box represents the lipid bilayer. The transmembrane proteins are exposed on both sides of the membrane; anchored membrane proteins penetrate only one half of the lipid bilayer; associated membrane proteins bind to transmembrane proteins as part of a complex; and skeletal membrane proteins form a network underneath the plasma membrane that can give shape to a cell.
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 Further Reading
    book Alberts B, Johnson A, Lewis J et al. (2007) The Molecular Biology of the Cell, 5th edn. New York: Garland Press.
    book Vance DE and Vance J (2008) Biochemistry of Lipids, Lipoproteins and Membranes, 5th edn. Amsterdam: Elsevier.
    book Yeagle PL (2005) The Structure of Biological Membranes, 2nd edn. Boca Raton, FL: CRC Press.

Related Sub-Topics:

Cell Membranes | Membrane Proteins | Lipids and Membrane Structure | Molecular Transport | Lipids: Structure, Function, Metabolism
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Article Title: Cell Membrane Features
 
How to Cite close
Yeagle, Philip L(Dec 2009) Cell Membrane Features. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0001261.pub2]