Nuclear Receptor Coactivator 3 (NCOA3)

NCOA3 is a transcriptional coactivator protein which contains several nuclear receptor interacting domains and an intrinsic histone acetyltransferase activity. NCOA3 is recruited to DNA promotion sites by ligand activated nuclear receptors. NCOA3 in turn acylates histones which makes downsteam DNA more accessible to transcription. Hence NCOA3 assists nuclear receptors in the upregulation of gene expression.

This variant, which they called AIB-delta-3, encodes a 130-kD protein lacking the N-terminal basic helix-loop-helix domain and the first of the 2 PAS dimerization domains of full-length AIB1. Northern and Western blot analyses detected higher AIB-delta-3 expression in breast tumor samples and cell lines than in normal breast tissue.