Cryoelectron microscopy and cryoelectron tomography of the nuclear pre-mRNA processing machine

Ohad Medalia, Dieter Typke, Reiner Hegerl, Mina Angenitzki, Joseph Sperling, Ruth Sperling

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Large nuclear ribonucleoprotein particles, which can be viewed as the naturally assembled precursor messenger RNA (pre-mRNA) processing machine, were analyzed in frozen-hydrated preparations by cryoelectron microscopy. A general and reproducible strategy for preparing ice-embedded large nuclear ribonucleoprotein (lnRNP) particles at sufficiently high concentration was developed. Taking advantage of their negatively charged components, the lnRNP particles are adsorbed and thus concentrated on a positively charged lipid monolayer while preserving their native structure. Using this approach we carried out cryoelectron tomography and three-dimensional image reconstruction of individual lnRNP particles. The study revealed a structure similar to that of negatively stained particles studied previously, yet with additional features. The small additional domain visualized in negative stain appeared to be larger in the ice preparations. In addition, using image restoration from focus series of ice-embedded lnRNP particles, new features such as holes within the subunits were visualized in two dimensions, and it was shown that the subunits are interconnected via a fiber, very likely formed by the pre-mRNA. This finding supports the model that each subunit represents a spliceosome that splices out the intron wound around it.

Original languageEnglish
Pages (from-to)74-84
Number of pages11
JournalJournal of Structural Biology
Issue number1-2
StatePublished - 20 Nov 2002
Externally publishedYes


  • Charged lipid monolayer
  • Cryoelectron microscopy
  • Cryoelectron tomography
  • Image restoration
  • Pre-mRNA processing
  • Three-dimensional image reconstruction
  • lnRNP complexes

ASJC Scopus subject areas

  • Structural Biology


Dive into the research topics of 'Cryoelectron microscopy and cryoelectron tomography of the nuclear pre-mRNA processing machine'. Together they form a unique fingerprint.

Cite this