Histone deacetylases and SAP18, a novel polypeptide, are components of a human Sin3 complex

Article Abstract:

A new Rb-associated polypeptide, mSin3-associated polypeptide (SAP18) was identified by using the Western blot analysis and was isolated from HDAC1 and HDAC2 by using microsequencing. In vitro interaction between SAP18 and mSin3 was established using radiolabeled transcription-translation system, while in vivo interaction was demonstrated by using immunoprecipitation. Furthermore, it was found that SAP18 can influence the synthesis of a repressive complex thus, promoting mSin3-HDAC1-mediated transcriptional repression.

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Siah2 regulates stability of prolyl-hydroxylases, controls HIF1 alpha abundance, and modulates physiological responses to hypoxia

Article Abstract:

The novel mechanism underlying the increase in hypoxia-inducible factor-1 (HIF1) alpha expression during hypoxic conditions is examined. The regulation of abundance of prolyl hydroxylase domain 1(PHD1) and prolyl hydroxylase domain 3 (PHD3) via their targeting for proteasome-dependent degradation by the E3 ubiquitin ligases Siah 1a/2 is demonstrated under hypoxia conditions.

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Multiple mechanisms confining RNA polymerase II ubiquitylation to polymerases undergoing transcriptional arrest

Article Abstract:

Highly purified factors were used to reconstitute RNA polymerase II (RNAPII) ubiquitylation in vitro in order to study mechanisms and regulation of RNAPII ubiquitylation and degradation. The results identify several mechanisms that confine ubiquitylation of RNAPII to the forms of the enzyme that arrest during elongation.

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