Phospho-HP1γ (Ser83) Antibody

• 产品编号：CST-2600S      品牌：CST       原厂货号：2600S
• 产品分类：抗体 > 一抗 > 磷酸化抗体
• 应用分类：

描述：

Phospho-HP1γ (Ser83) Antibody检测仅在Ser83 (又被称为未加工的HP1γ蛋白Ser93位点)位点磷酸化的内源性HP1γ蛋白。该抗体不能与HP1α或HP1β蛋白发生交叉反应。通过合成的与人源HP1γ蛋白Ser83位点周围相应的多肽片段去免疫动物从而制备出此多克隆抗体。通过多肽亲和层析纯化获得。

Heterochromatin protein 1 (HP1)作为一类异染色质调节因子参与了基因的沉默和染色质高级结构（1）。HP1家族总共有三个成员（α, β和γ），它们主要和异染色质的着丝粒相结合；但是HP1β和γ也在基因组的常染色质中存在（2，3）。HP1蛋白大约有25KD，并且都有保守的氨基酸末端染色质结构域，后面跟了一个可变的铰链区和一个保守的碳末端chromoshadow结构域。染色质结构域可以帮助结合到在Lys9位点发生了3甲基化的H3上，这是一个和着丝粒异染色质密切相关的组蛋白“标志”（4,5）。这个可变的铰链区可以通过sequence-independent的方式与RNA、DNA结合（6）。Chromoshadow 结构域除了结合包括SUV39 Hhistone methyltransferase、DNMT1、DNMT3a DNA methyltransferases 以及 the p150 subunit of chromatin-assembly factor-1 (CAF1) 在内的多种与基因沉默和异染色质形成的蛋白外，还介导HP1蛋白的二聚体化（7-9）。除了参与异染色质的形成和扩展，HP1和SUV39H同样也发现和retinoblastoma (Rb)与 E2F6 proteins这两种在静止期细胞中抑制基因转录的蛋白共同形成复合物（10,11）。HP1蛋白受到多种翻译后修饰包括：磷酸化，乙酰化，甲基化，泛素化和苏木化，这表明有多重调节方式（12-14）。

在体外通过蛋白激酶A(PKA)使HP1γ蛋白Ser83位点磷酸化，并且在体内通过forskolin和IBMX处理使PKA的激活可导致HP1γ蛋白磷酸化(14)。通过Phospho-HP1γ (Ser83) Antibody证明在有丝分裂期HP1γ蛋白在Ser83位点磷酸化水平增加，结果显示在未处理的有丝分裂细胞中免疫荧光染色增加，并且在使用紫杉醇处理的有丝分裂停滞的细胞中免疫印迹(Western blot)信号增加。Ser83位点的磷酸化仅发现在HP1γ蛋白的一个亚群，而HP1γ发现与常染色质有关联，特别是HP1γ能结合到活化基因的编码区域(14)。这个磷酸化减弱HP1γ蛋白沉默转录水平的能力，并且可能是转录延伸的一个标记物 (14)。

1. Maison, C. and Almouzni, G. (2004) Nat. Rev. Mol. Cell Biol. 5, 296-304.
2. Minc, E. et al. (2000) Cytogenet. Cell Genet. 90, 279-284.
3. Nielsen, A.L. et al. (2001) Mol. Cell 7, 729-739.
4. Lachner, M. et al. (2001) Nature 410, 116-120.
5. Bannister, A.J. et al. (2001) Nature 410, 120-124.
6. Muchardt, C. et al. (2002) EMBO Rep. 3, 975-981.
7. Yamamoto, K. and Sonoda, M. (2003) Biochem. Biophys. Res. Commun. 301, 287-292.
8. Fuks, F. et al. (2003) Nucleic Acids Res. 31, 2305-2312.
9. Murzina, N. et al. (1999) Mol. Cell 4, 529-540.
10. Nielsen, S.J. et al. (2001) Nature 412, 561-565.
11. Ogawa, H. et al. (2002) Science 296, 1132-1136.
12. Minc, E. et al. (1999) Chromosoma 108, 220-234.
13. Zhao, T. et al. (2001) J. Biol. Chem. 276, 9512-9518.
14. Lomberk, G. et al. (2006) Nat. Cell Biol. 8, 407-415.

原厂资料：

Homology

Species predicted to react based on 100% sequence homology: D. melanogaster, Bovine, Horse

Specificity / Sensitivity

Phospho-HP1γ (Ser83) Antibody detects endogenous levels of HP1γ protein only when phosphorylated on Ser83 (also referred to as Ser93 of the unprocessed form of HP1γ). This antibody does not cross-react with HP1α or HP1β proteins.

Source / Purification

Polyclonal antibodies are produced by immunizing animals with a synthetic phosphopeptide corresponding to amino acids surrounding Ser83 of human HP1γ. Antibodies are purified by affinity chromatography.

Background

Heterochromatin protein 1 (HP1) is a family of heterochromatic adaptor molecules involved in both gene silencing and higher order chromatin structure (1). All three HP1 family members (α, β and γ) are primarily associated with centromeric heterochromatin; however, HP1β and γ also localize to euchromatic sites in the genome (2,3). HP1 proteins are approximately 25 kDa in size and each contains a conserved amino-terminal chromodomain, followed by a variable hinge region and a conserved carboxy-terminal chromoshadow domain. The chromodomain facilitates binding to histone H3 tri-methylated on Lys9, a histone "mark" closely associated with centromeric heterochromatin (4,5). The variable hinge region binds both RNA and DNA in a sequence-independent manner (6). The chromoshadow domain mediates the dimerization of HP1 proteins, in addition to binding multiple proteins implicated in gene silencing and heterochromatin formation, including the SUV39H histone methyltransferase, the DNMT1 and DNMT3a DNA methyltransferases and the p150 subunit of chromatin-assembly factor-1 (CAF1) (7-9). In addition to contributing to heterochromatin formation and propagation, HP1 and SUV39H are also found complexed with retinoblastoma (Rb) and E2F6 proteins, both of which function to repress euchromatic gene transcription in quiescent cells (10,11). HP1 proteins are subject to multiple types of post-translational modifications, including phosphorylation, acetylation, methylation, ubiquitination and sumoylation, suggesting multiple means of regulation (12-14).

HP1γ is phosphorylated on Ser83 by protein kinase A (PKA) in vitro, and activation of PKA by forskolin and IBMX treatment leads to increased phosphorylation in vivo (14). Phosphorylation of HP1γ on Ser83 also increases during mitosis as demonstrated by the Phospho-HP1γ (Ser83) Antibody, which shows increased immunofluorescent staining in untreated mitotic cells and increased Western blot signal in lysates from cells arrested in mitosis by treatment with paclitaxel. Phosphorylation of Ser83 only occurs on a subpopulation of HP1γ found associated with euchromatin, specifically HP1γ bound to coding regions of active genes (14). 
This phosphorylation impairs the ability of HP1γ to silence transcription and may be a marker for transcription elongation (14).

1. Maison, C. and Almouzni, G. (2004) Nat. Rev. Mol. Cell Biol. 5, 296-304.
2. Minc, E. et al. (2000) Cytogenet. Cell Genet. 90, 279-284.
3. Nielsen, A.L. et al. (2001) Mol. Cell 7, 729-739.
4. Lachner, M. et al. (2001) Nature 410, 116-120.
5. Bannister, A.J. et al. (2001) Nature 410, 120-124.
6. Muchardt, C. et al. (2002) EMBO Rep. 3, 975-981.
7. Yamamoto, K. and Sonoda, M. (2003) Biochem. Biophys. Res. Commun. 301, 287-292.
8. Fuks, F. et al. (2003) Nucleic Acids Res. 31, 2305-2312.
9. Murzina, N. et al. (1999) Mol. Cell 4, 529-540.
10. Nielsen, S.J. et al. (2001) Nature 412, 561-565.
11. Ogawa, H. et al. (2002) Science 296, 1132-1136.
12. Minc, E. et al. (1999) Chromosoma 108, 220-234.
13. Zhao, T. et al. (2001) J. Biol. Chem. 276, 9512-9518.
14. Lomberk, G. et al. (2006) Nat. Cell Biol. 8, 407-415.

注意事项：

Storage: Supplied in 10 mM HEPES (pH 7.5), 150 mM NaCl,
100 µg/ml BSA and 50% glycerol. Store at -20°C.
Do not aliquot the antibody.