- Heterochromatin protein 1
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chromobox homolog 5 Identifiers Symbol CBX5 Alt. symbols HP1-alpha Entrez 23468 HUGO 1555 OMIM 604478 RefSeq NM_012117 UniProt P45973 Other data Locus Chr. 12 q13.13 chromobox homolog 1 Identifiers Symbol CBX1 Alt. symbols HP1-beta Entrez 10951 HUGO 1551 OMIM 604511 RefSeq NM_006807 UniProt P83916 Other data Locus Chr. 17 q21.32 chromobox homolog 3 Identifiers Symbol CBX3 Alt. symbols HP1-gamma Entrez 11335 HUGO 1553 OMIM 604477 RefSeq NM_007276 UniProt Q13185 Other data Locus Chr. 7 p21-15 The family of Heterochromatin Protein 1 (HP1) ("Chromobox Homolog", CBX) are highly conserved adapter proteins, which have important functions in the cell nucleus. These functions include gene repression by heterochromatin formation, transcriptional activation, regulation of binding of cohesion complexes to centromere, sequesteration of genes to nuclear periphery, transcriptional arrest, maintenance of heterochromatin integrity, gene repression at single nucleosome level and gene repression by heterochromatization of euchromatin. HP1 proteins are fundamental units of heterochromatin packaging that are enriched at the centromeres and telomeres of nearly all Eukaryotic chromosomes with the notable exception of budding yeast, in which a yeast-specific silencing complex of SIR (silent information regulatory) proteins serve a similar function. Members of the HP1 family are characterized by an N-terminal chromodomain and a C-terminal chromoshadow domain, separated by a Hinge region. HP1 is also found at euchromatic sites, where its binding correlates with gene repression. HP1 was originally discovered by Dr. Tharappel C James and Dr. Sarah Elgin in 1986 as an important factor in the phenomenon known as position effect variegation in Drosophila melanogaster.[1][2]
Contents
Paralogs and Orthologs
Three different paralogs of HP1 are found in Drosophila melanogaster, HP1a, HP1b and HP1c. Subsequently orthologs of HP1 were also discovered in S. pombe (Swi6), Xenopus (Xhp1α and Xhp1γ) and Chicken (CHCB1, CHCB2 and CHCB3). In mammals,[3] there are three paralogs: HP1α, HP1β and HP1γ.
HP1β in mammals
HP1β interacts with the Histone-Methyltransferase (HMTase) Suv(3-9)h1 and is a component of both pericentric and telomeric heterochromatin.[4][5][6] HP1β is a dosage-dependent modifier of pericentric heterochromatin-induced silencing[7] and silencing is thought to involve a dynamic association of the HP1β chromodomain with the tri-methylated Histone H3 Me(3)K9H3.
HP1 Interacting Proteins
HP1 seems to interact with numerous other proteins/molecules with different cellular functions in different organisms. Some of these HP1 interacting partners are: Histone H1, Histone H3, Methylated K9 Histone H3, Histone H4, Histone methyltransferase, DNA methyltransferase, Methyl CpG binding protein MeCP2, and the origin recognition complex protein ORC2
See also
References
- ^ James, T.C. & S.C Elgin (1986). "Identification of a nonhistone chromosomal protein associated with heterochromatin in Drosophila melanogaster and its gene". Mol. Cell. Biol. 6 (11): 3862–3872. PMC 367149. PMID 3099166. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=367149.
- ^ Eissenberg, J.C., James, T.C., Foster-Hartnett, D.M., Hartnett, T., Ngan, V.K.W., Craig, C., Elgin, S.C.R. (1990). "Mutation in a heterochromatin-specific chromosomal protein is associated with suppression of position-effect variegation in Drosophila melanogaster". Proceedings of the National Academy of Sciences of the United States of America 87 (24): 9923–7. doi:10.1073/pnas.87.24.9923. PMC 55286. PMID 2124708. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=55286.
- ^ Singh PB, Miller JR, Pearce J, Kothary R, Burton RD, Paro R, James TC, Gaunt SJ. (February 1991). "A sequence motif found in a Drosophila heterochromatin protein is conserved in animals and plants". Nucleic Acids Res. 19 (4): 789–94. doi:10.1093/nar/19.4.789. PMC 333712. PMID 1708124. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=333712.
- ^ Aagaard L, Laible G, Selenko P, Schmid M, Dorn R, Schotta G, Kuhfittig S, Wolf A, Lebersorger A, Singh PB, Reuter G, Jenuwein T. (April 1999). "Functional mammalian homologues of the Drosophila PEV-modifier Su(var)3-9 encode centromere-associated proteins which complex with the heterochromatin component M31". EMBO J. 18 (7): 1923–38. doi:10.1093/emboj/18.7.1923. PMC 1171278. PMID 10202156. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1171278.
- ^ Wreggett KA, Hill F, James PS, Hutchings A, Butcher GW, Singh PB (1994). "A mammalian homologue of Drosophila heterochromatin protein 1 (HP1) is a component of constitutive heterochromatin". Cytogenet. Cell Genet. 66 (2): 99–103. doi:10.1159/000133676. PMID 8287692.
- ^ Sharma GG, Hwang KK, Pandita RK, Gupta A, Dhar S, Parenteau J, Agarwal M, Worman HJ, Wellinger RJ, Pandita TK. (Nov; 2003). "Human Heterochromatin Protein 1 Isoforms HP1Hsα and HP1Hsβ Interfere with hTERT-Telomere Interactions and Correlate with Changes in Cell Growth and Response to Ionizing Radiation". Mol. Cell. Biol. 23 (22): 8363–76. doi:10.1128/MCB.23.22.8363-8376.2003. PMC 262350. PMID 14585993. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=262350.
- ^ Festenstein R, Sharghi-Namini S, Fox M, Roderick K, Tolaini M, Norton T, Saveliev A, Kioussis D, Singh P (December 1999). "Heterochromatin protein 1 modifies mammalian PEV in a dose- and chromosomal-context-dependent manner". Nat. Genet. 23 (4): 457–61. doi:10.1038/70579. PMID 10581035.
Further reading
- Singh PB, Georgatos SD (Oct-Dec 2002). "HP1: facts, open questions, and speculation". J. Struct. Biol. 140 (1–3): 10–6. doi:10.1016/S1047-8477(02)00536-1. PMID 12490149. Review
Transcription factors and intracellular receptors (1) Basic domains (1.1) Basic leucine zipper (bZIP)Activating transcription factor (AATF, 1, 2, 3, 4, 5, 6, 7) · AP-1 (c-Fos, FOSB, FOSL1, FOSL2, JDP2, c-Jun, JUNB, JUND) · BACH (1, 2) · BATF · BLZF1 · C/EBP (α, β, γ, δ, ε, ζ) · CREB (1, 3, L1) · CREM · DBP · DDIT3 · GABPA · HLF · MAF (B, F, G, K) · NFE (2, L1, L2, L3) · NFIL3 · NRL · NRF (1, 2, 3) · XBP1(1.2) Basic helix-loop-helix (bHLH)ATOH1 · AhR · AHRR · ARNT · ASCL1 · BHLHB2 · BMAL (ARNTL, ARNTL2) · CLOCK · EPAS1 · FIGLA · HAND (1, 2) · HES (5, 6) · HEY (1, 2, L) · HES1 · HIF (1A, 3A) · ID (1, 2, 3, 4) · LYL1 · MESP2 · MXD4 · MYCL1 · MYCN · Myogenic regulatory factors (MyoD, Myogenin, MYF5, MYF6) · Neurogenins (1, 2, 3) · NeuroD (1, 2) · NPAS (1, 2, 3) · OLIG (1, 2) · Pho4 · Scleraxis · SIM (1, 2) · TAL (1, 2) · Twist · USF1(1.3) bHLH-ZIP(1.4) NF-1(1.5) RF-X(1.6) Basic helix-span-helix (bHSH)(2) Zinc finger DNA-binding domains (2.1) Nuclear receptor (Cys4)subfamily 1 (Thyroid hormone (α, β), CAR, FXR, LXR (α, β), PPAR (α, β/δ, γ), PXR, RAR (α, β, γ), ROR (α, β, γ), Rev-ErbA (α, β), VDR)
subfamily 2 (COUP-TF (I, II), Ear-2, HNF4 (α, γ), PNR, RXR (α, β, γ), Testicular receptor (2, 4), TLX)
subfamily 3 (Steroid hormone (Androgen, Estrogen (α, β), Glucocorticoid, Mineralocorticoid, Progesterone), Estrogen related (α, β, γ))
subfamily 4 NUR (NGFIB, NOR1, NURR1) · subfamily 5 (LRH-1, SF1) · subfamily 6 (GCNF) · subfamily 0 (DAX1, SHP)(2.2) Other Cys4(2.3) Cys2His2General transcription factors (TFIIA, TFIIB, TFIID, TFIIE (1, 2), TFIIF (1, 2), TFIIH (1, 2, 4, 2I, 3A, 3C1, 3C2))
ATBF1 · BCL (6, 11A, 11B) · CTCF · E4F1 · EGR (1, 2, 3, 4) · ERV3 · GFI1 · GLI-Krüppel family (1, 2, 3, REST, S2, YY1) · HIC (1, 2) · HIVEP (1, 2, 3) · IKZF (1, 2, 3) · ILF (2, 3) · KLF (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17) · MTF1 · MYT1 · OSR1 · PRDM9 · SALL (1, 2, 3, 4) · SP (1, 2, 4, 7, 8) · TSHZ3 · WT1 · Zbtb7 (7A, 7B) · ZBTB (16, 17, 20, 32, 33, 40) · zinc finger (3, 7, 9, 10, 19, 22, 24, 33B, 34, 35, 41, 43, 44, 51, 74, 143, 146, 148, 165, 202, 217, 219, 238, 239, 259, 267, 268, 281, 295, 300, 318, 330, 346, 350, 365, 366, 384, 423, 451, 452, 471, 593, 638, 644, 649, 655)(2.4) Cys6(2.5) Alternating composition(3) Helix-turn-helix domains (3.1) HomeodomainARX · CDX (1, 2) · CRX · CUTL1 · DBX (1, 2) · DLX (3, 4, 5) · EMX2 · EN (1, 2) · FHL (1, 2, 3) · HESX1 · HHEX · HLX · Homeobox (A1, A2, A3, A4, A5, A7, A9, A10, A11, A13, B1, B2, B3, B4, B5, B6, B7, B8, B9, B13, C4, C5, C6, C8, C9, C10, C11, C12, C13, D1, D3, D4, D8, D9, D10, D11, D12, D13) · HOPX · IRX (1, 2, 3, 4, 5, 6, MKX) · LMX (1A, 1B) · MEIS (1, 2) · MEOX2 · MNX1 · MSX (1, 2) · NANOG · NKX (2-1, 2-2, 2-3, 2-5, 3-1, 3-2, 6-1, 6-2) · NOBOX · PBX (1, 2, 3) · PHF (1, 3, 6, 8, 10, 16, 17, 20, 21A) · PHOX (2A, 2B) · PITX (1, 2, 3) · POU domain (PIT-1, BRN-3: A, B, C, Octamer transcription factor: 1, 2, 3/4, 6, 7, 11) · OTX (1, 2) · PDX1 · SATB2 · SHOX2 · VAX1 · ZEB (1, 2)(3.2) Paired box(3.3) Fork head / winged helix(3.4) Heat Shock Factors(3.5) Tryptophan clusters(3.6) TEA domain(4) β-Scaffold factors with minor groove contacts (4.1) Rel homology region(4.2) STAT(4.3) p53(4.4) MADS box(4.6) TATA binding proteins(4.7) High-mobility group(4.10) Cold-shock domainCSDA, YBX1(4.11) Runt(0) Other transcription factors (0.2) HMGI(Y)(0.3) Pocket domain(0.6) MiscellaneousCategories:- Genes on chromosome 12
- Genes on chromosome 17
- Genes on chromosome 7
- Transcription factors
- Epigenetics
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