Nucleoplasmin: Difference between revisions
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=Structural highlights= | =Structural highlights= | ||
Nucleoplasmin (NP) is made out of five <scene name='46/467273/Np_monomer/1'>monomers</scene>,that create ring-shaped histone chaperone. The monomers are formed by a <scene name='46/467273/Core_domain/1'>core domain</scene> that responsible for oligomerization, that make the protein highly stable and compact. | Nucleoplasmin (NP) is made out of five <scene name='46/467273/Np_monomer/1'>monomers</scene>,that create ring-shaped histone chaperone. The monomers are formed by a <scene name='46/467273/Core_domain/1'>core domain</scene> that responsible for oligomerization, that make the protein highly stable and compact. | ||
The activation of NP is by strong destabilization of the pentamer, probably due to electrostatic repulsion. The NP needs compact and stable structure so he can accumulate negative charges that weakens its quaternary interactions, and its required for its biological function. | The NP core is made out of eight beta strands that form a barrel with a jellyroll topology. Residues in the hydrophobic core are highly conserved (aproximate 80%). The AKDE and GSGP motifs are ordered loops and may function in decamer formation. | ||
[[Image:NP core.jpg|thumb|NP core]] | |||
The activation of NP is by strong destabilization of the pentamer, probably due to electrostatic repulsion. The NP needs compact and stable structure so he can accumulate negative charges that weakens its quaternary interactions, and its required for its biological function. Those segments contained poly-glu and a nuclear localization signal (NLS), and it is thought to adopt a | |||
natively disordered conformation. | |||
== Decamer core == | |||
The stability is provided by | |||
== Activation by Phosphorylation == | |||
NP decondensate the chromatin by the poly-glu tail, Phosphorylation on the core domain is also required for efficient decondensation. Partial phosphorylation can give the protein the ability to bind core histones, but only hyperphosphorylation of specific regions of both protein domains can make the decondensation process to begin. | |||
= orthologey in Homo sapiens = | = orthologey in Homo sapiens = | ||
the NP in Humans is made out of <scene name='46/467273/Dimer/1'>dimer</scene> while each <scene name='46/467273/Monomer/2'>monomer</scene> consisted of five chains. The structure remain similiar to the one in Xenopus but with a change in amino acids in its <scene name='46/467273/Core_domain/2'>core domain</scene>, Val insted of Ile. | the NP in Humans is made out of <scene name='46/467273/Dimer/1'>dimer</scene> while each <scene name='46/467273/Monomer/2'>monomer</scene> consisted of five chains. The structure remain similiar to the one in Xenopus but with a change in amino acids in its <scene name='46/467273/Core_domain/2'>core domain</scene>, Val insted of Ile. | ||
The Decamer bind H2A-H2B dimers and H3-H4 tetramers simultaneously, In the absence of histone tetramers the pentamer binds H2A-H2B and formes central hub. When H3-H4 tetramers are recruited this results in a functional dimerization of the complex, and the decamer being formed. | The Decamer bind H2A-H2B dimers and H3-H4 tetramers simultaneously, In the absence of histone tetramers the pentamer binds H2A-H2B and formes central hub. When H3-H4 tetramers are recruited this results in a functional dimerization of the complex, and the decamer being formed. | ||
== conservastion == | == conservastion == | ||
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5. Platonova, O., Akey, I.V., Head, J.F., Akey, C.W.Crystal structure and function of human nucleoplasmin (npm2): a histone chaperone in oocytes and embryos.Biochemistry.2011 Sep 20;50(37):8078-89. | 5. Platonova, O., Akey, I.V., Head, J.F., Akey, C.W.Crystal structure and function of human nucleoplasmin (npm2): a histone chaperone in oocytes and embryos.Biochemistry.2011 Sep 20;50(37):8078-89. | ||
PMCID:PMC3172369 DOI:10.1021/bi2006652 | PMCID:PMC3172369 DOI:10.1021/bi2006652 | ||
6. Sonia Ban˜ uelos,Miren J. Omaetxebarria, Isbaal Ramos,Martin R. Larsen, Igor Arregi, Ole N. Jensen, Jesus M. Arizmendi, Adelina Prado, and Arturo Muga. Phosphorylation of Both Nucleoplasmin Domains Is Required | |||
for Activation of Its Chromatin Decondensation Activity. THE JOURNAL OF BIOLOGICAL CHEMISTRY VOL. 282, NO. 29, pp. 21213–21221, July 20, 2007 | |||