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Heterogeneous nuclear ribonucleoprotein U (scaffold attachment factor A)
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols HNRNPU ; HNRPU; SAF-A; U21.1; hnRNP U
External IDs OMIM602869 MGI1858195 HomoloGene22991 GeneCards: HNRNPU Gene
RNA expression pattern
PBB GE HNRPU 200593 s at tn.png
PBB GE HNRPU 200594 x at tn.png
PBB GE HNRPU 216855 s at tn.png
More reference expression data
Species Human Mouse
Entrez 3192 51810
Ensembl ENSG00000153187 ENSMUSG00000039630
UniProt Q00839 Q8VEK3
RefSeq (mRNA) NM_004501 NM_016805
RefSeq (protein) NP_004492 NP_058085
Location (UCSC) Chr 1:
245.01 – 245.03 Mb
Chr 1:
178.32 – 178.34 Mb
PubMed search [1] [2]

Heterogeneous nuclear ribonucleoprotein U is a protein that in humans is encoded by the HNRNPU gene.[1][2]

This gene belongs to the subfamily of ubiquitously expressed heterogeneous nuclear ribonucleoproteins (hnRNPs). The hnRNPs are RNA binding proteins and they form complexes with heterogeneous nuclear RNA (hnRNA). These proteins are associated with pre-mRNAs in the nucleus and appear to influence pre-mRNA processing and other aspects of mRNA metabolism and transport. While all of the hnRNPs are present in the nucleus, some seem to shuttle between the nucleus and the cytoplasm. The hnRNP proteins have distinct nucleic acid binding properties. The protein encoded by this gene contains a RNA binding domain and scaffold-associated region (SAR)-specific bipartite DNA-binding domain. This protein is also thought to be involved in the packaging of hnRNA into large ribonucleoprotein complexes. During apoptosis, this protein is cleaved in a caspase-dependent way. Cleavage occurs at the SALD site, resulting in a loss of DNA-binding activity and a concomitant detachment of this protein from nuclear structural sites. But this cleavage does not affect the function of the encoded protein in RNA metabolism. At least two alternatively spliced transcript variants have been identified for this gene.[3]


HNRPU has been shown to interact with NDN,[4] EP300,[5] Glucocorticoid receptor[6] and GTF2F1.[7]


  1. ^ Fackelmayer FO, Richter A (Mar 1994). "hnRNP-U/SAF-A is encoded by two differentially polyadenylated mRNAs in human cells". Biochim Biophys Acta 1217 (2): 232–4. doi:10.1016/0167-4781(94)90044-2. PMID 7509195. 
  2. ^ Fackelmayer FO, Richter A (Sep 1994). "Purification of two isoforms of hnRNP-U and characterization of their nucleic acid binding activity". Biochemistry 33 (34): 10416–22. doi:10.1021/bi00200a024. PMID 8068679. 
  3. ^ "Entrez Gene: HNRNPU heterogeneous nuclear ribonucleoprotein U (scaffold attachment factor A)". 
  4. ^ Taniura, Hideo; Yoshikawa Kazuaki (2002). "Necdin interacts with the ribonucleoprotein hnRNP U in the nuclear matrix". J. Cell. Biochem. (United States) 84 (3): 545–55. doi:10.1002/jcb.10047. ISSN 0730-2312. PMID 11813259. 
  5. ^ Martens, Joost H A; Verlaan Matty; Kalkhoven Eric; Dorsman Josephine C; Zantema Alt (Apr 2002). "Scaffold/matrix attachment region elements interact with a p300-scaffold attachment factor A complex and are bound by acetylated nucleosomes". Mol. Cell. Biol. (United States) 22 (8): 2598–606. doi:10.1128/MCB.22.8.2598-2606.2002. ISSN 0270-7306. PMC 133732. PMID 11909954. 
  6. ^ Eggert, M; Michel J; Schneider S; Bornfleth H; Baniahmad A; Fackelmayer F O; Schmidt S; Renkawitz R (Nov 1997). "The glucocorticoid receptor is associated with the RNA-binding nuclear matrix protein hnRNP U". J. Biol. Chem. (UNITED STATES) 272 (45): 28471–8. doi:10.1074/jbc.272.45.28471. ISSN 0021-9258. PMID 9353307. 
  7. ^ Kim, M K; Nikodem V M (Oct 1999). "hnRNP U inhibits carboxy-terminal domain phosphorylation by TFIIH and represses RNA polymerase II elongation". Mol. Cell. Biol. (UNITED STATES) 19 (10): 6833–44. ISSN 0270-7306. PMC 84680. PMID 10490622. 

Further reading[edit]