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Sci. Signal., 1 April 2008
Vol. 1, Issue 13, p. pe16
[DOI: 10.1126/stke.113pe16]


SRC-3 Transcription-Coupled Activation, Degradation, and the Ubiquitin Clock: Is There Enough Coactivator to Go Around in Cells?

David M. Lonard and Bert W. O’Malley*

Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.

Abstract: Overexpression of nuclear receptor coactivators is a frequent event in breast cancer cells and is recognized as a key mechanism for these cells to maximize their oncogenic growth state. Steroid receptor coactivator–3 [(SRC-3), also known as amplified in breast cancer–1 or AIB1] is foremost among these overexpressed oncogenic coactivators, being overexpressed in most breast cancers. Because of its oncogenic potential, normal cells must carefully control its cellular concentration. We discuss how SRC-3 quantitatively influences estrogen-regulated gene transcription when it is at limiting concentrations in normal breast cells and at nonlimiting concentrations in breast cancer cells. Precise control of the cellular concentration of SRC-3 may thus serve as a mechanism for defining growth responses to estrogen receptors and other growth-promoting transcription factors.

*Corresponding author. E-mail, berto{at}

Citation: D. M. Lonard, B. W. O’Malley, SRC-3 Transcription-Coupled Activation, Degradation, and the Ubiquitin Clock: Is There Enough Coactivator to Go Around in Cells? Sci. Signal. 1, pe16 (2008).

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