| Our proteomic study of purified human nucleoli
identified several novel proteins, including Paraspeckle Protein
1 (PSP1). PSP1 accumulates in a nucleoplasmic compartment, termed
paraspeckle, that also contains at least two other RNA-binding
protein components, PSP2 and p54/nrb. A similar pattern of typically
10-20 paraspeckles was detected in all human cell types analysed,
including primary and transformed cells. |
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Paraspeckles correspond to discrete bodies in
the interchromatin nucleoplasmic space that are often located
adjacent to splicing speckles (see above). The three paraspeckle
proteins relocalise quantitatively to unique cap structures
at the nucleolar periphery when transcription is inhibited (see
left; RNA staining of the nucleolus is in red). |
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