To bead or not to bead? Lens-specific intermediate filaments revisited

Spyros D. Georgatos, Fotini Gounari, George Goulielmos, Ueli Aebi

Research output: Contribution to journalReview articlepeer-review


For nearly three decades cytoplasmic intermediate filaments (IFs) have been described as 10 nm thick, unbranched ropes radiating from the cell nucleus and extending to the plasma membrane. This stereotype is now being challenged by the discovery and molecular characterization of the beaded filaments (BFs), a novel class of IFs composed of the lens-specific proteins filensin and phakinin. In contrast to 'mainstream' IFs, BFs have a distinctly nodular appearance and form a meshwork underneath the plasma membrane of the lens fiber cells. In vitro assembly studies, expression of filensin and phakinin in cultured cells, and analysis of the corresponding genes reveal that these proteins have evolved from two different subfamilies of IF proteins, thus yielding a unique structure. The new information provides a basis for understanding how the various forms of tissue-specific IF proteins might have developed adopting to the constraints of a specialized environment.

Original languageEnglish (US)
Pages (from-to)2629-2634
Number of pages6
JournalJournal of cell science
Issue number21
StatePublished - 1997


  • Beaded filament
  • Cytoskeleton
  • Electron microscopy
  • Eye lens
  • Filensin
  • In vitro assembly
  • Intermediate filament
  • Phakinin

ASJC Scopus subject areas

  • Cell Biology


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