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scaffold associated region (SAR)

Loci of DNA where the nuclear matrix attaches. Site of attachment of topoisomerase 2 forming the base of loops associated with gene clusters. Function: - constitute anchor points of DNA for the chromatin scaffold - serve to organize chromatin into structural domains - role in regulation of gene expression - S/MAR separate a transcriptional domain) from its neighbors, but also & provide a nidus for the assembly of factors enabling transcriptional events within a transcriptional domain - apparently an S/MAR may be either constitutive or facultative - ~64,000 S/MAR (transcriptional domains) plus an additional ~10,000 S/MAR (replication foci) per cell nucleus Structure: - occur at the flanks of transcribed regions, in 5 -introns, & at breakpoint cluster regions (BCR) - no obvious consensus sequence

General

transcription factor binding site

Properties

NAME: scaffold associated region

References

  1. Molecular Cell Biology (2nd ed) Darnell J; Lodish H & Baltimore D (eds), Scientific American Books, WH Freeman, NY 1990, pg 338
  2. Bode et al Science 255:195 1992
  3. Wikipedia: Scaffold/matrix attachment region http://en.wikipedia.org/wiki/Scaffold/matrix_attachment_region