Even weirder, according to that Wikipedia article, it doesn't appear to be necessary, or has very non-obvious implications when it's removed. Yet, it's present in almost all eucaryote cells...
I'd like to point out that any protein that is produced takes up precious resources. Our evolutionary intuition suggests that unnecessary things should be dropped from the genome.
Suppose a protein is unnecessary. Then there would be no evolutionary pressure to keep it from mutating and loosing its function(and mutations happen all the time!). The organisms would just gradually loose it to mutations and we wouldn't find a conserved protein throughout eucaryotes. So there must be something keeping it.