User:Alisa Cario

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The cytoskeleton brings structure to the cell, is integral in cell division, and aids in migration. One of the constitutive parts of the cytoskeleton are microtubules. Microtubules are polymerized from tubulin subunits that incorporate into a hollow cylindrical structure linked together by lateral and vertical hydrogen bonds. Each tubulin subunit is made from a heterodimer of alpha and beta tubulin. Both alpha and beta tubulin are known to bind to GTP. However, only the beta subunit hydrolyzes GTP, which occurs once incorporated into microtubules. The beta tubulin hydrolysis of GTP to GDP is known to destabilize microtubules. Microtubules have polarity where one end of microtubule, called the plus end, has a greater affinity to add tubulin subunits than the other end, called the minus end. Microtubules are inherently dynamic, going through periods of depolymerization, known as catastrophe, and then return to polymerization, known as rescue. Microtubules can also go through a process called treadmilling, where the length of the microtubule does not change but the rate of polymerization at the plus end equals the rate of depolymerization at the minus end. There are a number of microtubule associated proteins (MAPs) that are known to regulate the dynamics of microtubules. Some examples of this include MAPTau, MAP2 and stathmin. See [[tubulin]], [[tau]].
The cytoskeleton brings structure to the cell, is integral in cell division, and aids in migration. One of the constitutive parts of the cytoskeleton are microtubules. Microtubules are polymerized from tubulin subunits that incorporate into a hollow cylindrical structure linked together by lateral and vertical hydrogen bonds. Each tubulin subunit is made from a heterodimer of alpha and beta tubulin. Both alpha and beta tubulin are known to bind to GTP. However, only the beta subunit hydrolyzes GTP, which occurs once incorporated into microtubules. The beta tubulin hydrolysis of GTP to GDP is known to destabilize microtubules. Microtubules have polarity where one end of microtubule, called the plus end, has a greater affinity to add tubulin subunits than the other end, called the minus end. Microtubules are inherently dynamic, going through periods of depolymerization, known as catastrophe, and then return to polymerization, known as rescue. Microtubules can also go through a process called treadmilling, where the length of the microtubule does not change but the rate of polymerization at the plus end equals the rate of depolymerization at the minus end. There are a number of microtubule associated proteins (MAPs) that are known to regulate the dynamics of microtubules. Some examples of this include MAPTau, MAP2 and stathmin. See [[tubulin]], [[tau]].
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[[Image:Stathmin_figure_cario1.png|center|thumb| upright=3| Figure 1. Adapted from ''Ruben 2004''. Stathmin, in purple, can bind to tubulin dimers to prevent polymerization or to microtubules to increase the rate of catastrophe. ]]
 
== '''Evolutionary conservation''' ==
== '''Evolutionary conservation''' ==
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<scene name='77/778894/Stathmin/1'>Stathmin</scene>, also known as oncoprotein 18 or metablastin, is a 19kDa microtubule associated protein known to destabilize microtubules <ref>PMID:8598048</ref>. Stathmin belongs to a larger family of stathmin-like proteins. These proteins are cell cycle and developmentally regulated, known to play a role in proliferation, differentiation, and function of cells <ref>PMID:9312271</ref> <ref>PMID: 9880330</ref>. Stathmin family proteins can bind to <scene name='77/778894/Highlight_of_tubulin/1'>tubulin dimers</scene> to inhibit polymerization or can bind to the microtubule to enhance the rate of catastrophe<ref>PMID:8598048</ref>
<scene name='77/778894/Stathmin/1'>Stathmin</scene>, also known as oncoprotein 18 or metablastin, is a 19kDa microtubule associated protein known to destabilize microtubules <ref>PMID:8598048</ref>. Stathmin belongs to a larger family of stathmin-like proteins. These proteins are cell cycle and developmentally regulated, known to play a role in proliferation, differentiation, and function of cells <ref>PMID:9312271</ref> <ref>PMID: 9880330</ref>. Stathmin family proteins can bind to <scene name='77/778894/Highlight_of_tubulin/1'>tubulin dimers</scene> to inhibit polymerization or can bind to the microtubule to enhance the rate of catastrophe<ref>PMID:8598048</ref>
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[[Image:Stathmin_figure_cario1.png|center|thumb| upright=3| Figure 1. Adapted from ''Ruben 2004''. Stathmin, in purple, can bind to tubulin dimers to prevent polymerization or to microtubules to increase the rate of catastrophe. ]]
'''Mitosis''': Stathmin's role in the cell cycle progression is characterized. During interphase, microtubules are relatively stable. However during the onset of mitosis, stathmin is upregulated to increase the rate of catastrophe of microtubules, causing them to become more dynamic. Stathmin has also been shown to bind and sequester two tubulin heterodimers, reducing the amount of available tubulin to polymerize microtubules <ref>PMID:9312271</ref>. However, as mitosis progresses, microtubules must repolymerize to form the mitotic spindle. Stathmin is regulated during this process by phosphorylation <ref>PMID: 7982983</ref> <ref>PMID: 1737801</ref>. There are four known <scene name='77/778894/Stathmin_phospho/1'>phosphorylation sites of stathmin</scene>, serine 16, serine 25, serine 38, and serine 63 which are known to be a target of cyclin-dependent kinases <ref>PMID: 8376365</ref> <ref>PMID: 9271428</ref>. Stathmin overexpression prevents mitotic spindle formation where inhibition interferes with later stages in mitosis <ref>PMID: 10022911</ref>.
'''Mitosis''': Stathmin's role in the cell cycle progression is characterized. During interphase, microtubules are relatively stable. However during the onset of mitosis, stathmin is upregulated to increase the rate of catastrophe of microtubules, causing them to become more dynamic. Stathmin has also been shown to bind and sequester two tubulin heterodimers, reducing the amount of available tubulin to polymerize microtubules <ref>PMID:9312271</ref>. However, as mitosis progresses, microtubules must repolymerize to form the mitotic spindle. Stathmin is regulated during this process by phosphorylation <ref>PMID: 7982983</ref> <ref>PMID: 1737801</ref>. There are four known <scene name='77/778894/Stathmin_phospho/1'>phosphorylation sites of stathmin</scene>, serine 16, serine 25, serine 38, and serine 63 which are known to be a target of cyclin-dependent kinases <ref>PMID: 8376365</ref> <ref>PMID: 9271428</ref>. Stathmin overexpression prevents mitotic spindle formation where inhibition interferes with later stages in mitosis <ref>PMID: 10022911</ref>.

Revision as of 13:09, 30 April 2018

* Full Real Name: Alisa Cario

  • Position: Graduate Student
  • Institution (NO ABBREVIATIONS): University of Vermont
  • City, State/Province, Country: Burlington, VT USA
  • Field of Expertise or Study: Creation of protopedia page for a class project. The class is Proteins 1 under Dr. Stephen Everse


Stathmin-4 (RB3) bound to Tubulin stabilized with Vinblastine 

4eb6

Structure of stathmin bound to two tubulin heterodimers at 3.47Å resolution. Tubulin dimers are stabilized by vinblastin, shown by grey spheres between heterodimers. (PDB entry 4eb6)

Drag the structure with the mouse to rotate

Proteopedia Page Contributors and Editors (what is this?)

Alisa Cario, Eric Martz

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