کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1951444 | 1055767 | 2008 | 8 صفحه PDF | دانلود رایگان |
Nucleolar organiser regions (NORs) are comprised of tandem arrays of ribosomal gene (rDNA) repeats that are transcribed by RNA polymerase I (Pol I), ultimately resulting in formation of a nucleolus. Upstream binding factor (UBF), a DNA binding protein and component of the Pol I transcription machinery, binds extensively across the rDNA repeat in vivo. Pseudo-NORs are tandem arrays of a heterologous DNA sequence with high affinity for UBF introduced into human chromosomes. In this review we describe how analysis of pseudo-NORs has provided important insights into nucleolar formation. Pseudo-NORs mimic endogenous NORs in a number of important respects. On metaphase chromosomes both appear as secondary constrictions comprised of undercondensed chromatin. The transcriptional silence of pseudo-NORs provides a platform for studying the transcription independent recruitment of factors required for nucleolar formation by this specialised chromatin structure. During interphase, pseudo-NORs appear as distinct and novel sub-nuclear bodies. Analysis of these bodies and comparison to their endogenous counterpart has provided insights into nucleolar formation and structure.
Journal: Biochimica et Biophysica Acta (BBA) - Molecular Cell Research - Volume 1783, Issue 11, November 2008, Pages 2116–2123