Monday, April 2, 2018
In depth analysis of the effect of phosphorylation and pH(!?!?) on ubiquitin!
You know what I was just thinking? The ubiquitin process in mammalian cells just wasn't anywhere near complex enough....
...you know what we need? A modification on the ubiquitin modification itself that has far reaching biological impacts on whatever ubiquitination is doing in the first place!
This great new study didn't discover Serine-65 phosphorylation, but they go far out of their way to figure out what the heck it does -- and -- it's complicated.
You won't find much mass spec here. I think they only used it to confirm they'd purified phosphorylated ubiquitin from the unmodified variant. Most of the work here is NMR (i.e., I'm not real confident in any interpretation I could draw from their results, so I won't say too much about them) but pH is also involved here -- yikes -- 'cause it affects the charge on the phosphate group (making me just a little concerned that this isn't something we think about in terms of phosphoproteomics when we chemically enrich them and drop them in formic acid -- are we losing tons of biologically relevant information -- and could our technology ever possibly get us to it -- maybe neutral or negative phosphoproteomics?!?) And the longest sentence ever award goes to....
This makes sense, though, right? And maybe it is something to think about. Because not only does the phosphorylation change the 3D structures here, but so does the charge on the phosphorylations. Great paper and something I'll be thinking about all day!