The elementary RNP fiber — not the higher order structure — determines the all‐or‐none disintegration behaviour of balbiani ring pre‐messenger RNP particles upon RNase A treatment
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Media type:
E-Article
Title:
The elementary RNP fiber — not the higher order structure — determines the all‐or‐none disintegration behaviour of balbiani ring pre‐messenger RNP particles upon RNase A treatment
Description:
<jats:p><jats:bold>Summary—</jats:bold> Balbiani ring premessenger ribonucleoprotein (RNP) particles are built from a 7‐nm RNP fiber which is tightly folded into a ring‐shaped RNP ribbon. Isolated particles are known to disintegrate in an all‐or‐none fashion upon RNase A treatment. In the present study we investigated whether this mode of disintegration is dependent on an intact particle structure or is inherent in the 7‐nm fiber. When treated at low ionic strength, the Balbiani ring (BR) particles lost their higher order structure and the 7‐nm fiber was unpacked, as evidenced by sucrose gradient sedimentation and electron microscopy. When treated with RNase A, unfolded as well as intact particles disintegrated in the all‐or‐none fashion, with similar kinetics and without apparent intermediates. Proteinase K treatment, however, obliterated this pattern: the protein‐free particle RNA degraded progressively. As the typical disintegration pattern of the particles was not altered by unfolding, but was lost by deproteinization, the all‐or‐none mode of disintegration is likely to be a property of the 7‐nm RNP fiber.</jats:p>