While Lund and Dahlberg haven't demonstrated that these enzymes do in fact get into the nucleus, it's clear that must happen for the aminoacylation to occur, says Schimmel. It suggests there's a huge amount of traffic going in and out of the nucleus. And that of course raises more questions. Those enzymes are made in the cytoplasm, Hopper comments. And they get into the nucleus.
Nobody has a clue how that happens.
Already at least one pathway has been found. The protein was first reported to function this way by Simos et al. The explosion of information from the Human Genome Project will also provide information for researchers exploring nuclear transport, remarks Schimmel. Part of that information deluge will include protein sequences. One of the first things you do is ask if these sequences are related to sequences of other proteins that we do know something about.