Metaphase chromosome structure: bands arise from a differential folding path of the highly AT-rich scaffold

Cell. 1994 Feb 25;76(4):609-22. doi: 10.1016/0092-8674(94)90502-9.


Using the highly AT-specific fluorochrome daunomycin, a longitudinal optical signal called AT queue, thought to arise from a line-up of the highly AT-rich scaffold-associated regions (SARs) by the scaffolding, was identified in native chromosomes. Fluorescence banding is proposed to result from a differential folding path of the AT queue during its progression from telomere to telomere. The AT queue is tightly coiled or folded in a Q band, the resulting transverse striations across the chromatid, which also represent Giemsa subbands, generating a bright AT-rich signal over the Q region. The R bands, in contrast, contain a more central (unfolded) AT queue, yielding an AT-dull signal over the R regions. The AT queue is identified by immunofluorescence against topoisomerase II (topo II) and HMG-I/Y as the scaffold of native chromosomes; the fluorescence signal from both proteins is akin to a detailed Q-type banding pattern. Native chromosomes appear assembled according to the loop-scaffold model.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Composition
  • Chromatin / ultrastructure
  • Chromosome Banding / methods*
  • Chromosomes / ultrastructure*
  • DNA Topoisomerases, Type II / metabolism
  • Daunorubicin
  • Deer
  • High Mobility Group Proteins / metabolism
  • Metaphase*
  • Staining and Labeling


  • Chromatin
  • High Mobility Group Proteins
  • DNA Topoisomerases, Type II
  • Daunorubicin