Splicing factors (green) are found around rDNA transcription sites (red).

Splicing factors, usually associated with RNA polymerase II transcripts, have a temporary home near sites of RNA polymerase I transcription, as shown on page 51 by Bubulya et al.

During interphase, premRNA splicing factors such as the serine arginine–rich (SR) proteins reside in nuclear speckles, along with other pre-mRNA processing proteins. The speckles disassemble during mitosis, and then reform in G1. By viewing speckle reformation, the group finds that SR proteins first make a side trip and gather in nucleolar organizing region–associated patches (NAPs), around areas where rDNA is transcribed.

Inhibiting mRNA transcription prolonged the life of NAPs and also caused SR proteins to accumulate near nucleoli in interphase cells. Without their pre-mRNA transcript targets available, SR protein traffic was backed up at a location it would otherwise move through rapidly.

NAPs contained hypophosphorylated SR...

The Rockefeller University Press
2004
The Rockefeller University Press
2004
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