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Protein PSIP1 PDB 1z9e.png
Available structures
PDB Ortholog search: PDBe RCSB
Aliases PSIP1, DFS70, LEDGF, PAIP, PSIP2, p52, p75, PC4 and SFRS1 interacting protein 1
External IDs MGI: 2142116 HomoloGene: 13242 GeneCards: PSIP1
RNA expression pattern
PBB GE PSIP1 210758 at fs.png

PBB GE PSIP1 205961 s at fs.png

PBB GE PSIP1 209337 at fs.png
More reference expression data
Species Human Mouse
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC) Chr 9: 15.46 – 15.51 Mb Chr 4: 83.46 – 83.49 Mb
PubMed search [1] [2]
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PC4 and SFRS1 interacting protein 1, also known as lens epithelium-derived growth factor (LEDGF/p75), dense fine speckles 70kD protein (DFS 70) or transcriptional coactivator p75/p52, is a protein that in humans is encoded by the PSIP1 gene.[3][4]


PSIP1 has not been clearly linked to a specific cellular mechanism. The term LEDGF/p75 (Lens epithelium-derived growth factor) has entered common usage based on the initial characterization of PSIP1, however this is a misnomer, as the protein is present in most tissues and has no direct role in the development of lens epithelium. LEDGF/p75, a transcription coactivator, gained prominence as a host factor that assists HIV integration[5] and is probably the only integrase interactor whose knock-down severely affects the HIV integration levels.[6][7][8] The interaction between HIV integrase and human LEDGF/p75 is a promising target for anti-HIV drug discovery.[9] LEDGF/p75 recruits MLL complexes to HOX genes to regulate their expression.[10] LEDGF/p52 is shown to recruit splicing factors to H3K36 trimethylated chromatin to modulate alternative splicing,[11] also regulates HOTTIP lncRNA, which is shown to regulate HOX genes in cis.[12]


LEDGF/p75 is a 60kDa, 530-amino-acid-long protein.[13] The N-terminal portion of the protein consists of a PWWP domain, a nuclear localization sequence, and two copies of the AT-hook DNA binding motif. The C-terminal portion of LEDGF/p75 contains a structure termed the integrase-binding domain,[14] which interacts with lentiviral integrase proteins as well as numerous cellular proteins. The N-terminal portion interacts strongly with chromatin, making LEDGF/p75 a constitutively nuclear protein. An isoform of the protein, LEDGF/p52, is produced by alternative splicing. LEDGF/p52 shares the N-terminal 325 amino acids of LEDGF/p75 but lacks the integrase-binding domain.


PSIP1 has been shown to interact with the proteins ASF/SF2, JPO2, Cdc7-Dbf4, and POGZ as well as the menin/MLL protein complex.[15][16]


  1. ^ "Human PubMed Reference:". 
  2. ^ "Mouse PubMed Reference:". 
  3. ^ "Entrez Gene: PSIP1 PC4 and SFRS1 interacting protein 1". 
  4. ^ Singh DP, Kimura A, Chylack LT, Shinohara T (January 2000). "Lens epithelium-derived growth factor (LEDGF/p75) and p52 are derived from a single gene by alternative splicing". Gene. 242 (1-2): 265–73. PMID 10721720. doi:10.1016/S0378-1119(99)00506-5. 
  5. ^ Cherepanov P, Maertens G, Proost P, Devreese B, Van Beeumen J, Engelborghs Y, De Clercq E, Debyser Z (January 2003). "HIV-1 integrase forms stable tetramers and associates with LEDGF/p75 protein in human cells". J. Biol. Chem. 278 (1): 372–81. PMID 12407101. doi:10.1074/jbc.M209278200. 
  6. ^ Vandekerckhove L, Christ F, Van Maele B, De Rijck J, Gijsbers R, Van den Haute C, Witvrouw M, Debyser Z (February 2006). "Transient and stable knockdown of the integrase cofactor LEDGF/p75 reveals its role in the replication cycle of human immunodeficiency virus". J. Virol. 80 (4): 1886–96. PMC 1367129Freely accessible. PMID 16439544. doi:10.1128/JVI.80.4.1886-1896.2006. 
  7. ^ Shun MC, Raghavendra NK, Vandegraaff N, Daigle JE, Hughes S, Kellam P, Cherepanov P, Engelman A (July 2007). "LEDGF/p75 functions downstream from preintegration complex formation to effect gene-specific HIV-1 integration". Genes Dev. 21 (14): 1767–78. PMC 1920171Freely accessible. PMID 17639082. doi:10.1101/gad.1565107. 
  8. ^ Llano M, Saenz DT, Meehan A, Wongthida P, Peretz M, Walker WH, Teo W, Poeschla EM (October 2006). "An essential role for LEDGF/p75 in HIV integration". Science. 314 (5798): 461–4. PMID 16959972. doi:10.1126/science.1132319. 
  9. ^ Christ F, Voet A, Marchand A, Nicolet S, Desimmie BA, Marchand D, Bardiot D, Van der Veken NJ, Van Remoortel B, Strelkov SV, De Maeyer M, Chaltin P, Debyser Z (June 2010). "Rational design of small-molecule inhibitors of the LEDGF/p75-integrase interaction and HIV replication". Nat. Chem. Biol. 6 (6): 442–8. PMID 20473303. doi:10.1038/nchembio.370. 
  10. ^ Pradeepa, Madapura M.; Grimes, Graeme R.; Taylor, Gillian C. A.; Sutherland, Heidi G.; Bickmore, Wendy A. (2014-08-18). "Psip1/Ledgf p75 restrains Hox gene expression by recruiting both trithorax and polycomb group proteins". Nucleic Acids Research. 42 (14): 9021–9032. ISSN 0305-1048. PMC 4132756Freely accessible. PMID 25056311. doi:10.1093/nar/gku647. 
  11. ^ Pradeepa, Madapura M.; Sutherland, Heidi G.; Ule, Jernej; Grimes, Graeme R.; Bickmore, Wendy A. (2012-05-17). "Psip1/Ledgf p52 Binds Methylated Histone H3K36 and Splicing Factors and Contributes to the Regulation of Alternative Splicing". PLOS Genetics. 8 (5): e1002717. ISSN 1553-7404. PMC 3355077Freely accessible. PMID 22615581. doi:10.1371/journal.pgen.1002717. 
  12. ^ Pradeepa, Madapura M.; McKenna, Fionnuala; Taylor, Gillian C. A.; Bengani, Hemant; Grimes, Graeme R.; Wood, Andrew J.; Bhatia, Shipra; Bickmore, Wendy A. (2017-04-06). "Psip1/p52 regulates posterior Hoxa genes through activation of lncRNA Hottip". PLOS Genetics. 13 (4): e1006677. ISSN 1553-7404. PMC 5383017Freely accessible. PMID 28384324. doi:10.1371/journal.pgen.1006677. 
  13. ^ Llano M, Morrison J, Poeschla EM (2009). "Virological and cellular roles of the transcriptional coactivator LEDGF/p75". Curr. Top. Microbiol. Immunol. 339: 125–46. PMC 3093762Freely accessible. PMID 20012527. doi:10.1007/978-3-642-02175-6_7. 
  14. ^ Cherepanov P, Sun ZY, Rahman S, Maertens G, Wagner G, Engelman A (June 2005). "Solution structure of the HIV-1 integrase-binding domain in LEDGF/p75". Nat. Struct. Mol. Biol. 12 (6): 526–32. PMID 15895093. doi:10.1038/nsmb937. 
  15. ^ Ge H, Si Y, Wolffe AP (December 1998). "A novel transcriptional coactivator, p52, functionally interacts with the essential splicing factor ASF/SF2". Mol. Cell. 2 (6): 751–9. PMID 9885563. doi:10.1016/S1097-2765(00)80290-7. 
  16. ^ Hughes S, Jenkins V, Dar MJ, Engelman A, Cherepanov P (January 2010). "Transcriptional co-activator LEDGF interacts with Cdc7-activator of S-phase kinase (ASK) and stimulates its enzymatic activity". J. Biol. Chem. 285 (1): 541–54. PMC 2804203Freely accessible. PMID 19864417. doi:10.1074/jbc.M109.036491. 

Further reading[edit]