Classes
| Core histone H2A/H2B/H3/H4 | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| PDB rendering of H2AFJ based on 1aoi. | |||||||||
| Identifiers | |||||||||
| Symbol | Histone | ||||||||
| Pfam | PF00125 | ||||||||
| Pfam clan | CL0012 | ||||||||
| InterPro | IPR007125 | ||||||||
| SCOP | 1hio | ||||||||
| SUPERFAMILY | 1hio | ||||||||
|
|||||||||
| linker histone H1 and H5 family | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| PDB rendering of HIST1H1B based on 1ghc. | |||||||||
| Identifiers | |||||||||
| Symbol | Linker_histone | ||||||||
| Pfam | PF00538 | ||||||||
| InterPro | IPR005818 | ||||||||
| SMART | SM00526 | ||||||||
| SCOP | 1hst | ||||||||
| SUPERFAMILY | 1hst | ||||||||
|
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Five major families of histones exist: H1/H5, H2A, H2B, H3, and H4. Histones H2A, H2B, H3 and H4 are known as the core histones, while histones H1 and H5 are known as the linker histones.
Two of each of the core histones assemble to form one octameric nucleosome core particle, and 147 base pairs of DNA wrap around this core particle 1.65 times in a left-handed super-helical turn. The linker histone H1 binds the nucleosome and the entry and exit sites of the DNA, thus locking the DNA into place and allowing the formation of higher order structure. The most basic such formation is the 10 nm fiber or beads on a string conformation. This involves the wrapping of DNA around nucleosomes with approximately 50 base pairs of DNA separating each pair of nucleosomes (also referred to as linker DNA). The assembled histones and DNA is called chromatin. Higher-order structures include the 30 nm fiber (forming an irregular zigzag) and 100 nm fiber, these being the structures found in normal cells. During mitosis and meiosis, the condensed chromosomes are assembled through interactions between nucleosomes and other regulatory proteins.
The following is a list of human histone proteins:
| Super family | Family | Subfamily | Members |
|---|---|---|---|
| Linker | |||
| H1 | |||
| H1F | H1F0, H1FNT, H1FOO, H1FX | ||
| H1H1 | HIST1H1A, HIST1H1B, HIST1H1C, HIST1H1D, HIST1H1E, HIST1H1T | ||
| Core | |||
| H2A | |||
| H2AF | H2AFB1, H2AFB2, H2AFB3, H2AFJ, H2AFV, H2AFX, H2AFY, H2AFY2, H2AFZ | ||
| H2A1 | HIST1H2AA, HIST1H2AB, HIST1H2AC, HIST1H2AD, HIST1H2AE, HIST1H2AG, HIST1H2AI, HIST1H2AJ, HIST1H2AK, HIST1H2AL, HIST1H2AM | ||
| H2A2 | HIST2H2AA3, HIST2H2AC | ||
| H2B | |||
| H2BF | H2BFM, H2BFS, H2BFWT | ||
| H2B1 | HIST1H2BA, HIST1H2BB, HIST1H2BC, HIST1H2BD, HIST1H2BE, HIST1H2BF, HIST1H2BG, HIST1H2BH, HIST1H2BI, HIST1H2BJ, HIST1H2BK, HIST1H2BL, HIST1H2BM, HIST1H2BN, HIST1H2BO | ||
| H2B2 | HIST2H2BE | ||
| H3 | |||
| H3A1 | HIST1H3A, HIST1H3B, HIST1H3C, HIST1H3D, HIST1H3E, HIST1H3F, HIST1H3G, HIST1H3H, HIST1H3I, HIST1H3J | ||
| H3A2 | HIST2H3C | ||
| H3A3 | HIST3H3 | ||
| H4 | |||
| H41 | HIST1H4A, HIST1H4B, HIST1H4C, HIST1H4D, HIST1H4E, HIST1H4F, HIST1H4G, HIST1H4H, HIST1H4I, HIST1H4J, HIST1H4K, HIST1H4L | ||
| H44 | HIST4H4 |
Read more about this topic: Histone
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