Spoke ring and anchorage of nuclear pore complex revealed by high resolution transmission electron microscopy

Abstract

Abstract. Using several different methods, the nuclear pore complex (NPC) was shown to be anchored in the nuclear envelope into the specific curved region, called pore membrane. Three transmembrane nucleoporins in the equatorial region of NPC contain hydrophobic stretches, which exhibit the ability to intersect the phospholipid bilayer. Using transmission electron microscopy, we observed three different evaluable morphological situations in the section through the NPC spoke ring (SR). We suppose that some sections are directed through one type of subunit that is responsible for anchoring. Other sections are directed through the second type of subunit that may provide pore membrane bending. Finally, the spoke ring is sectioned between aforementioned subunits where the pore membrane is best preserved. The proposed anchor is represented by the chains of protein complexes which replace phospholipid bilayer in a relatively large area. Second subunit, presumed bending module is represented by the bundles of chains copying the shape of the pore membrane from the side of the NPC. This work is based on very high resolution resulting in unique and complicated images of tangled and cut off protein chains, nevertheless, it provides insight into how some proteins interact with or replace the membrane.

Ultrastructure of mitochondrial nucleoid and its surroundings

“…This study provides a direct extension of our earlier work (Prachař 2010). New findings in this work result from the new high resolution method recently developed in our laboratory and described and discussed in detail in a previously published work (Prachař 2014).…”

“…The second setting is used for recording, and this favors high resolution without defects from radiation damage. This high resolution methodology was recently published in detail (Prachař 2014) and it is also discussed in the "Discussion" section.…”

Transmission electron microscopy method providing high resolution in the cell section without radiation damage

“…Detailed description of the microscope settings is presented in this work and also in previous works (Prachař, ). Since the second microscope setting is crucial for achieving high resolution, the scheme of electron trajectories is shown in Figure .…”

“…Our high resolution method is based on two microscope settings. This high resolution methodology was recently published in greater detail (Pracha r, 2012(Pracha r, , 2014(Pracha r, , 2016. It is reprinted here and some parts have been added.…”