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SPOC (Spen paralog and ortholog C-terminal) domain found in SMART/HDAC1-associated repressor protein (SHARP) and similar proteins SHARP, also called Msx2-interacting protein (MINT), or Spen homolog, is an estrogen-inducible transcriptional repressor that interacts directly with transcriptional corepressors silencing mediator for retinoid and thyroid receptor (SMRT)/nuclear receptor corepressor (NCoR), histone deacetylases (HDACs), and components of the NuRD complex. SHARP recruits HDAC activity and binds to the steroid receptor RNA coactivator SRA through four conserved N-terminal RNA recognition motifs (RRMs), also called RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), further suppressing SRA-potentiated steroid receptor transcription activity. Thus, SHARP has the capacity to modulate both liganded and nonliganded nuclear receptors. SHARP also has been identified as a component of transcriptional repression complexes in Notch/RBP-Jkappa signaling pathways. In addition to the N-terminal RRMs, SHARP possesses a C-terminal SPOC domain that binds to SMRT/NcoR. This model corresponds to the SPOC domain that is involved in developmental signaling and has also been proposed to be a phosphorylation binding module. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",