描述：
Acetyl-Histone H4 (Lys5) Antibody检测仅在Lys5位点乙酰化的内源性histone H4的蛋白水平。该抗体不能与lysines 8、12或16位点乙酰化的histone H4发生交叉反应。通过合成的与人源histone H4蛋白Lys5位点乙酰化的周围相应的片段去免疫动物从而制备出此多克隆抗体。通过蛋白A和多肽亲和层析纯化获得。
核小体是由四种中心组蛋白(H2A、H2B、H3和H4)组成，它是染色质的主要构件模块。起初被认为是一个DNA包装的静态支架，目前组蛋白已经被认为是一个动态蛋白，其经历多种形式的翻译后修饰，包括乙酰化作用、磷酸化作用、甲基化作用和泛素化作用(1,2)。组蛋白乙酰化作用主要发生在histones H2A (Lys5)、H2B (Lys5, 12, 15, and 20)、H3 (Lys9, 14, 18, 23, 27, and 56)和H4 (Lys5, 8, 12, and 16)的氨基端尾部结构域，并且对于组蛋白沉积、转录激活、DNA复制、重组和DNA修复有着重要作用(1-3)。组蛋白尾部的高度乙酰化中和了这些区域的正电荷，并且被认为弱化了组蛋白-DNA和核小体-核小体的相互作用，因此使核染色质不稳定以及增加了DNA与不同的DNA结合蛋白的接近程度(4,5)。此外，特定的赖氨酸残基乙酰化产生了停留点，这些位置有助于招募包含一个bromodomain蛋白，该区域能结合到乙酰化的赖氨酸残基(6)。许多转录和染色质调节蛋白包含bromodomains，并且可能被招募到基因启动子，在某种程度上通过乙酰化的组蛋白尾部结合。组蛋白乙酰化通过组蛋白乙酰化转移酶(HATs)介导，例如CBP/p300、GCN5L2、PCAF和Tip60，这些通过DNA结合蛋白因子招募到基因上从而有助于转录激活(3)。去乙酰化作用通过组蛋白去乙酰转移酶(HDAC和Sirtuin蛋白)介导，这将逆转乙酰化的影响，并且有助于转录抑制(7,8)。
通过多重HAT蛋白使Histone H4蛋白lysine 5位点乙酰化。在酵母中通过Esa1p或在哺乳动物细胞中通过Tip60乙酰化，这些可能有助于转录激活和DNA修复，包括非同源性末端接合（Non-homologous end joining）和复制耦合修复(9-12)。Histone H4蛋白lysine 5位点也通过 CBP/p300乙酰化，CBP/p300是一个HAT蛋白家族成员，它作为对于大量转录因子的一个转录共激活因子(13)。
原厂资料：
Homology
Species predicted to react based on 100% sequence homology: Chicken, D. melanogaster, Xenopus, Zebrafish, Bovine, Pig, Horse, C. elegans
Specificity / Sensitivity
Acetyl-Histone H4 (Lys5) Antibody detects endogenous levels of histone H4 only when acetylated on Lys5. This antibody does not cross-react with histone H4 acetylated on lysines 8, 12, or 16.
Source / Purification
Polyclonal antibodies are produced by immunizing animals with a synthetic peptide corresponding to the amino terminus of histone H4 in which Lys5 is acetylated. Antibodies are purified by protein A and peptide affinity chromatography.
Background
The nucleosome, made up of four core histone proteins (H2A, H2B, H3, and H4), is the primary building block of chromatin. Originally thought to function as a static scaffold for DNA packaging, histones have now been shown to be dynamic proteins, undergoing multiple types of post-translational modifications, including acetylation, phosphorylation, methylation, and ubiquitination (1,2). Histone acetylation occurs mainly on the amino-terminal tail domains of histones H2A (Lys5), H2B (Lys5, 12, 15, and 20), H3 (Lys9, 14, 18, 23, 27, and 56), and H4 (Lys5, 8, 12, and 16), and is important for the regulation of histone deposition, transcriptional activation, DNA replication, recombination, and DNA repair (1-3). Hyper-acetylation of the histone tails neutralizes the positive charge of these domains and is believed to weaken histone-DNA and nucleosome-nucleosome interactions, thereby destabilizing chromatin structure and increasing the access of DNA to various DNA-binding proteins (4,5). In addition, acetylation of specific lysine residues creates docking sites for a protein module called the bromodomain, which binds to acetylated lysine residues (6). Many transcription and chromatin regulatory proteins contain bromodomains, and may be recruited to gene promoters, in part, through binding of acetylated histone tails. Histone acetylation is mediated by histone acetyltransferases (HATs), such as CBP/p300, GCN5L2, PCAF, and Tip60, which are recruited to genes by DNA-bound protein factors to facilitate transcriptional activation (3). Deacetylation, which is mediated by histone deacetylases (HDAC and Sirtuin proteins), reverses the effects of acetylation and generally facilitates transcriptional repression (7,8).
Histone H4 lysine 5 is acetylated by multiple HAT proteins. Acetylation by Esa1p in yeast, or Tip60 in mammalian cells, may contribute to both transcriptional activation and DNA repair, including non-homologous end joining and replication-coupled repair (9-12). Histone H4 lysine 5 is also acetylated by CBP/p300, a family of HAT proteins that function as transcriptional co-activators for a large number of transcription factors (13).
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