I have a question about the ERAD pathway.

As far as I understand it, proteins undergo a check in the ER whether they are functional or not. This works via glycosylation patterns (?) and proteins that are in some way incorrectly structured get exported into the cytosol via Sec61p channel, where they are poly-ubiquitinylated and subsequently shredded by the proteasome.

Now, some bacterial toxins are more or less known to use this process to get exported to the cytosol, but are not ubiquitinylated. Any ideas on how that might work?

Please with literature sources, if possible. :-)

Question

I have a question about the ERAD pathway.

As far as I understand it, proteins undergo a check in the ER whether they are functional or not. This works via glycosylation patterns (?) and proteins that are in some way incorrectly structured get exported into the cytosol via Sec61p channel, where they are poly-ubiquitinylated and subsequently shredded by the proteasome.

Now, some bacterial toxins are more or less known to use this process to get exported to the cytosol, but are not ubiquitinylated. Any ideas on how that might work?

Please with literature sources, if possible. :-)

anonymous · Answer

@frostbite @mrdoldum @Abhisar

anonymous · Answer

UPDATE:

I know now that these toxins have massively reduced their lysine counts. Since ubiquitination happens on lysine residues, it increases their time in the cytosol.

Question remaining: How does the toxin signal the cell that it wants to be exported for degradation?