Being or Becoming the Golgi: Framework or Process?

The constancy of biological structures is undeniable, but some structures self-assemble and reach equilibria, whereas others self-organize and attain steady states that are far from equilibrium [ 1 Misteli T. The concept of self-organization in cellular architecture. J. Cell Biol. 2001; 155: 181-185 Crossref PubMed Scopus (380) Google Scholar ]. ‘The processes that occur within a self-organized structure are not underpinned by a rigid architectural framework; rather, they determine its organization.’ Current skirmishes in the Golgi ‘wars’ tilt exactly on this distinction: does a persistent matrix nucleate Golgi assembly or does the organelle self-organize from components as they are exported by the endoplasmic reticulum (ER)? Various agents that block protein export from the ER cause Golgi structure to be lost and Golgi components to relocalize to the ER. Thus, many consider the Golgi a self-organizing, energy-dissipating, dynamic organelle, the components of which are in continual flux between the membranes of the ER and Golgi. Against this tide, Graham Warren's lab has shown that a stable membrane scaffold might nucleate Golgi assembly. They find that, despite loss of Golgi integrity, a membrane compartment retains a specific subset of Golgi ‘matrix’ proteins and persists at the characteristic juxtanuclear Golgi location.