Targeting of a chromosomal protein to the nucleus and to lampbrush chromosome loops.

We have isolated a cDNA clone (SE5A) that encodes a protein on lampbrush chromosome loops of the newt Notophthalmus. In vitro-synthesized transcripts of this clone were injected into Xenopus oocytes, where they were efficiently translated. Most of the translated protein was imported into the oocyte nucleus, and some of it appeared on the chromosome loops. The translation product must contain information that permits its appropriate targeting first to the nucleus and then to the chromosome loops.