CREB-regulated transcription coactivator 3 (transducer of regulated cAMP response element-binding protein 3, TORC-3, transducer of CREB protein 3, CRTC3, TORC3)
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Function
- transcriptional coactivator for CREB1
- acts as a coactivator, in the SIK/TORC signaling pathway, being active when dephosphorylated & acts independently of CREB1 Ser-133 phosphorylation
- enhances the interaction of CREB1 with TAF4
- regulates the expression of specific CREB-activated genes such as the steroidogenic gene, StAR
- potent coactivator of PPARGC1A & inducer of mitochondrial biogenesis in muscle cells
- binding, as a tetramer, through its N-terminal region, with the bZIP domain of CREB1 enhances recruitment of TAF4 to the promoter, Arg-314 in the bZIP domain of CREB1 is essential for this interaction (putative)
- interacts, via the N-terminal with the ankyrin repeats of BCL3, to form a complex with CREB1 on CRE & TxRE responsive elements & represses HTLV-1 LTR-mediated transcription
Structure
belongs to the TORC family
Compartment
Alternative splicing
named isoforms=4
Expression
- predominantly expressed in B-cells & T-cells
- highest levels in lung
- also expressed in brain, colon, heart, kidney, ovary, & prostate
- weak expression in liver, pancreas, muscle, small intestine, spleen & stomach
Pathology
- coactivator for TAX activation of the human T-cell leukemia virus type 1 (HTLV-1) long terminal repeats (LTR)
- interaction with HTLV-1 TAX enhances its transcriptional activity