Today another silly post (due to lack of time required for serious discussion). Over the weekend, I read three different texts, all dealing with the attachment of ubiquitin to proteins. As usual, the authors could not agree on a single name for this process. Some people call it “ubiquitination”, others call it “ubiquitylation” and yet others (including myself) use either one or the other, depending on daytime, temper, moon phase, or whatever. Some people actually combine the best of both worlds and say “ubiquitinylation”. So, one of the most pressing questions in the field of ubiquitinology remains: which one is correct?
First, let us consult the wisdom of the masses. A quick search by Google shows that at least in the discipline, ubiquitination wins hands-down. Here is the score: ubiquitination: 1.36 Mio hits, ubiquitylation: 0.22 Mio hits, ubiquitinylation 0.07 Mio hits. If we rather trust the scientists, the relation looks similar (but with much smaller numbers) . A pubmed search yielded ubiquitination : 4063 hits, ubiquitylation: 562 hits, ubiquitinylation 134 hits. Oh, and there is also ubiquination: 34 hits. The latter word reminds me of that confused ISMB07 speaker, who found in some text mining effort an enrichment of the term “ubiquinone” and told the audience that meant a link to regulated protein degradation. We can count ourselves lucky that ubiquinone and ubiquinol don’t get conjugated to proteins – this saves us from ubiquinolation, ubiquinonylation and the like. To my surprise, Pubmed doesn’t know of a single instance of ubiquinylation.
So, should we all use ubiquination? I don’t know. For people with a background in chemistry (like myself) ubiquitylation might be more attractive, likening ubiquitin to the functional groups that you can attach to a substance (methyl-, alkyl-, aryl-, hydroxyl-) The same reasoning would work for ubiquitinylation, although in most functional groups the original ending gets clipped off before the ‘yl’ suffix is applied. We don’t say “methanyl” for the “methyl” groups. A second argument in favor of ubiquitylation is a perceived consistence with other ubiquitin-like modifiers. Sumo does sumoylation, Nedd8 does neddylation, Urm1 does urmylation (or does it?), ISG15 does Isgylation, and so on. Not quite sure what Fat10 does. Fatylation? Fattenylation? Fatuation?
Nevertheless, most people (including myself, most of the time) use “ubiquitination”, and one good reason for that is a positive feedback loop. People are using it because this is what they read in most of the literature. A similar mechanism governs choice of desktop computer operating systems. I wonder if the folks who use ‘ubiquitylation’ are also using Macs?