SFPQ Antibody

Storage Buffer: PBS supplemented with 0.1% sodium azide, 50% glycerol, pH 7.3. Store at -20°C. Avoid repeated freeze-thaw cycles.

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SFPQ

P23246

SFPQ (Splicing Factor, Proline- and Glutamine-Rich) is a DNA- and RNA-binding protein crucial for various nuclear processes. It functions as an essential pre-mRNA splicing factor, playing a vital role in early spliceosome formation and the catalytic step II of splicing, likely as a heteromer with NONO. SFPQ binds pre-mRNA within the spliceosome C complex, exhibiting specific affinity for intronic polypyrimidine tracts. It participates in regulating signal-induced alternative splicing. In PTPRC/CD45 splicing, a phosphorylated form of SFPQ is sequestered by THRAP3 in resting T cells; T-cell activation and subsequent dephosphorylation lead to its release from THRAP3, enabling binding to pre-mRNA splicing regulatory elements and subsequent repression of exon inclusion. SFPQ interacts with U5 snRNA, potentially through binding to a purine-rich sequence near the 3' end of U5 snRNA stem 1b. It may be involved in a coupled pre-mRNA splicing and polyadenylation process, functioning within a snRNP-free complex with SNRPA/U1A. The SFPQ-NONO heteromer, in association with MATR3, may contribute to the nuclear retention of defective RNAs. SFPQ potentially participates in homologous DNA pairing, promoting in vitro ssDNA invasion between duplex DNA and forming D-loops. The SFPQ-NONO heteromer might modulate DNA unwinding by influencing topoisomerase I (TOP1) function; in vitro, it stimulates TOP1 dissociation from DNA after cleavage and enhances its translocation between DNA helices. This heteromer also binds DNA and may be involved in DNA non-homologous end joining (NHEJ), crucial for double-strand break repair and V(D)J recombination, potentially stabilizing paired DNA ends. In vitro studies demonstrate that the complex significantly stimulates DNA end joining, directly binds DNA substrates, and collaborates with the Ku70/XRCC5-Ku80 dimer to form a functional preligation complex. SFPQ also plays a role in transcriptional regulation, functioning as both a transcriptional activator and repressor. Transcriptional repression is mediated through SFPQ interaction with SIN3A and subsequent recruitment of histone deacetylases (HDACs). The SFPQ-NONO-NR5A1 complex binds the CYP17 promoter, regulating basal and cAMP-dependent transcriptional activity. The long isoform of SFPQ binds to the DNA-binding domains (DBDs) of nuclear hormone receptors (e.g., RXRA and potentially THRA), acting as a transcriptional corepressor in the absence of hormone ligands. It binds the 5'-CTGAGTC-3' DNA sequence in the insulin-like growth factor response element (IGFRE), inhibiting IGF-I-stimulated transcriptional activity. SFPQ also regulates the circadian clock, repressing the transcriptional activation of the CLOCK-ARNTL/BMAL1 heterodimer. It's essential for transcriptional repression of circadian target genes (e.g., PER1) mediated by the large PER complex via histone deacetylation. Finally, SFPQ is involved in nuclear speckle assembly and the regulation of DNA virus-mediated innate immune responses by integrating into the HDP-RNP complex, a platform for IRF3 phosphorylation and subsequent innate immune response activation through the cGAS-STING pathway.

SFPQ Research Highlights:

• Dimerization and Heterodimer Affinity: Analytical ultracentrifugation studies indicate that SFPQ-containing dimers dissociate at low micromolar concentrations, with heterodimers exhibiting higher affinity than homodimers. The SFPQ/PSPC1 heterodimer displays significantly higher affinity than the SFPQ/NONO heterodimer. (PMID: 29530979)
• Amyotrophic Lateral Sclerosis (ALS): SFPQ intron retention and nuclear loss are molecular hallmarks in familial and sporadic ALS. (PMID: 29789581)
• Cancer Research: Numerous studies link SFPQ to various cancers, exploring its roles in invasion, proliferation, and drug resistance through interactions with other proteins and RNAs. (See PMIDs: 29346433, 27259250, 28846091, 28315422, 26274027, 25025966, 24288667, 23618401, 19809274, 16832349)
• Viral Infections: SFPQ's interaction with viral RNA and its involvement in viral mRNA processing are highlighted in several studies. (See PMIDs: 28633417, 23158102, 22114566, 16938326)
• DNA Repair: SFPQ's role in DNA repair mechanisms, specifically non-homologous end joining (NHEJ), is established. (See PMIDs: 27924002, 21144806, 15590677)
• Transcriptional Regulation: SFPQ's complex roles in transcriptional regulation, acting as both an activator and repressor, are extensively explored. (See PMIDs: 21566083, 21106524, 17452459, 16731528, 19339282)
• RNA Processing and Splicing: Extensive research demonstrates SFPQ's multifaceted roles in RNA processing, splicing, and mRNA metabolism. (See PMIDs: 26261210, 25605962, 21881826, 16024807, 12403470, 12417296, 19447914)
• Other Cellular Processes: Additional studies investigate SFPQ's involvement in processes such as the circadian clock, innate immune response, and interactions with other proteins in various cellular pathways. (See PMIDs: 24507715, 22558197, 22156371, 20421735, 19874820, 12944487, 15668243, 18445785, 18655028, 17318576, 17537995, 17639083, 17965020)

HGNC: 10774

OMIM: 605199

KEGG: hsa:6421

STRING: 9606.ENSP00000349748

UniGene: Hs.355934

A chromosomal aberration involving SFPQ may be a cause of papillary renal cell carcinoma (PRCC). Translocation t(X;1)(p11.2;p34) with TFE3.

Nucleus speckle. Nucleus matrix. Cytoplasm.