Does the eukaryotic large ribosomal subunit have a channel passing through it?
The large ribosomal subunit of the thermophilic fungus Thermomyces lanuginosus was treated with 2.96 M NH4Cl to remove specific complements of ribosomal proteins, and the core particles thereby derived were imaged by bright field transmission electron microscopy, and recurring views computed by single particle electron image analysis. A new characteristic projection was elucidated which showed a large depression or channel passing through the subunit. Such a channel has been perceived in the prokaryotic large ribosomal subunit under certain conditions and has been postulated to be the exit pathway for the nascent polypeptide chain, but its existence has not hitherto been demonstrated in eukaryotes.
