Standard Article

In Vivo Analysis of Membrane Fusion

  1. Mark T Palfreyman,
  2. Erik M Jorgensen

Published Online: 15 MAR 2009

DOI: 10.1002/9780470015902.a0020891

eLS

eLS

How to Cite

Palfreyman, M. T. and Jorgensen, E. M. 2009. In Vivo Analysis of Membrane Fusion. eLS. .

Author Information

  1. University of Utah, Department of Biology and Howard Hughes Medical Institute, Salt Lake City, UT, USA

Publication History

  1. Published Online: 15 MAR 2009

Abstract

Membranes provide a barrier that allows chemical reactions to be isolated from the environment. The plasma membrane, for example, delineates self from nonself, and thus must have played an essential role in the evolution of life. Yet under numerous circumstances it is equally important that membranes be breached. Numerous forces oppose the spontaneous fusion of membranes; thus, specialized proteins have evolved to fuse membranes. The most well-understood fusion proteins are the viral fusion proteins and the SNARE proteins used in the secretory pathway. In addition, recent discoveries have lead to models for the fusion of organelles such as mitochondria and peroxisomes, as well as for cell–cell fusion. Despite the diverse structures of fusion proteins, it is possible that they function to drive membranes through a series of common lipid intermediates. Here we review the mechanisms of fusion for biological membranes, and highlight the similarities and differences in these processes.

Key concepts

  • Fusion proteins are thought to lead membranes through the common set of lipid intermediates: lipid stalk, hemifusion diaphragm and pore formation.

  • There are three known classes of viral fusogens: type I, II and III.

  • Type I and II are structurally unique yet undergo similar structural rearrangements during membrane fusion.

  • Viral fusion proteins are initially present only on a single membrane and must insert a fusion peptide into the target membrane to accomplish fusion.

  • SNAREs are used throughout the secretory pathway.

  • SNAREs are present on both membranes destined to fuse.

  • SNAREs and viral fusion proteins play an active role in all steps of the fusion process.

  • Multimerization of viral fusion proteins and SNARE proteins is needed for fusion to occur.

  • The fusogens used in cell–cell fusion are not evolutionarily conserved.

  • The coordinated action of Fzo1 and Mgm1 is needed to fuse the inner and outer membranes of mitochondria.

Keywords:

  • membrane fusion;
  • virus;
  • SNARE;
  • lipid;
  • fusogen