title: A thermodynamic model describing the nature of the crista junction: a structural motif in the mitochondrion.
abstract: The use of electron tomography has allowed the three-dimensional membrane topography of the mitochondrion to be better understood. The most striking feature of this topology is the crista junction, a structure that may serve to divide functionally the inner membrane and intermembrane spaces. In situ these junctions seem to have a preferred size and shape independent of the source of the mitochondrion with few exceptions. When mitochondria are isolated and have a condensed matrix the crista junctions enlarge and become nondiscrete. Upon permeation of the inner membrane and subsequent swelling of the matrix space, the uniform circular nature of the crista junction reappears. We examine the distribution of shapes and sizes of crista junctions and suggest a thermodynamic model that explains the distribution based on current theories of bilayer membrane shapes. The theory of spontaneous curvature shows the circular junction to be a thermodynamically stable structure whose size and shape is influenced by the relative volume of the matrix. We conclude that the crista junction exists predominantly as a circular junction, with other shapes as exceptions made possible by specific characteristics of the lipid bilayer.
authors.affiliation: Department of Biology, San Diego State University, San Diego, CA 92185, USA. renken@wadsworth.org
authors.forename: Christian
authors.initials: C
authors.lastname: Renken
authors.forename: Gino
authors.initials: G
authors.lastname: Siragusa
authors.forename: Guy
authors.initials: G
authors.lastname: Perkins
authors.forename: Lance
authors.initials: L
authors.lastname: Washington
authors.forename: Jim
authors.initials: J
authors.lastname: Nulton
authors.forename: Peter
authors.initials: P
authors.lastname: Salamon
authors.forename: Terrence G
authors.initials: TG
authors.lastname: Frey
mesh_terms: D000818:Animals; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007425:Intracellular Membranes / Q000648:ultrastructure; D008854:Microscopy, Electron; D008928:Mitochondria / Q000648:ultrastructure*; D008933:Mitochondrial Swelling; D008954:Models, Biological; D013816:Thermodynamics; D014057:Tomography, X-Ray Computed