ausblenden:
Schlagwörter:
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Zusammenfassung:
A backbone model of a 10-subunit yeast RNA polymerase II has been derived
from x-ray diffraction data extending to 3 angstroms resolution. All 10 subunits
exhibit a high degree of identity with the corresponding human proteins, and
9 of the 10 subunits are conserved among the three eukaryotic RNA polymerases
I, II, and III. Notable features of the model include a pair of jaws, formed
by subunits Rpb1, Rpb5, and Rpb9, that appear to grip DNA downstream of the
active center. A clamp on the DNA nearer the active center, formed by Rpb1,
Rpb2, and Rpb6, may be locked in the closed position by RNA, accounting for
the great stability of transcribing complexes. A pore in the protein complex
beneath the active center may allow entry of substrates for polymerization and
exit of the transcript during proofreading and passage through pause sites in
the DNA.
