Sandbox Reserved 995: Difference between revisions
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The <scene name='69/691537/Unita/1'>Aα subunit</scene> (or scaffolding subunit) along with the catalytic subunit makes up the core enzyme. Aα is composed of fifteen HEAT repeats that form a double layer of antiparallel alpha helices. The arrangement of the alpha helices causes the subunit to adopt a half circle shape. When in this conformation the Aα subunit is able to interact with the catalytic subunit via four-conserved HEAT repeats <ref> Xing, Yongna, Yanhui Xu, Yu Chen, Philip D. Jeffrey, Yang Chao, Zheng Lin, Zhu Li, Stefan Strack, Jeffry B. Stock, and Yigong Shi. "Structure of Protein Phosphatase 2A Core Enzyme Bound to Tumor-Inducing Toxins." Cell (2006): 341-53.</ref>, causing a conformational activation of the catalytic subunit and creation of the core enzyme | The <scene name='69/691537/Unita/1'>Aα subunit</scene> (or scaffolding subunit) along with the catalytic subunit makes up the core enzyme. Aα is composed of fifteen HEAT repeats that form a double layer of antiparallel alpha helices. The arrangement of the alpha helices causes the subunit to adopt a half circle shape. When in this conformation the Aα subunit is able to interact with the catalytic subunit via four-conserved HEAT repeats <ref> Xing, Yongna, Yanhui Xu, Yu Chen, Philip D. Jeffrey, Yang Chao, Zheng Lin, Zhu Li, Stefan Strack, Jeffry B. Stock, and Yigong Shi. "Structure of Protein Phosphatase 2A Core Enzyme Bound to Tumor-Inducing Toxins." Cell (2006): 341-53.</ref>, causing a conformational activation of the catalytic subunit and creation of the core enzyme | ||
The <scene name='69/691537/Unitc/1'>Cα subunit</scene> (Catalytic subunit) associates with the A subunit to form a heterodimer protein. The catalytic subunit (in conjunction with the scaffolding and regulatory subunits) can have many functions and is a particularly important factor in cell growth regulation, signal transduction regulation, and cellular development as well as playing a key role in suppressing uncontrolled cell proliferation. It thought that the B subunit is largely responsible for the specific function of the A-C dimer. | The <scene name='69/691537/Unitc/1'>Cα subunit</scene> (Catalytic subunit) associates with the A subunit to form a heterodimer protein. The catalytic subunit (in conjunction with the scaffolding and regulatory subunits) can have many functions and is a particularly important factor in cell growth regulation, signal transduction regulation, and cellular development as well as playing a key role in suppressing uncontrolled cell proliferation. It is thought that the B subunit is largely responsible for the specific function of the A-C dimer. | ||
In the case of PP2A holoenzyme the <scene name='69/691537/Unitb/1'>B Subunit</scene> (or regulatory subunit) is not part of the core enzyme but rather a coenzyme that associates with the Aα and Cα subunits to form the holoenzyme. This subunit structurally resembles the Aα scaffolding subunit; it contains eighteen alpha helixes stacked antiparallel to each other to cause a crescent structure. Of these eighteen alpha helixes eight of them resemble HEAT repeat motifs that are similar to repeats found on the Aα subunit. These conserved repeats are located on the, largely hydrophobic, convex side of the B subunit. The hydrophobic residues create a groove to which the Aα subunit loosely associates with, mainly via van der Waal interaction. The concave side of the B subunit consists of a variety of negatively charged amino acid residues, which create an isolated acidic environment. The acid nature of the concave side promotes multiple hydrogen bonds with residues from the Cα subunit. These hydrogen bonds coupled with a multitude of van der Waal interactions results in strong B -Cα subunit association. <ref>Xu, Y., Xing, Y., Chen, Y., Chao, Y., Lin, Z., Fan, E., Yu, J.W., Strack, S., Jeffery, P.D., Shi, Y. 2006. Structure of the protein phosphatase 2a holoenzyme. Cell (127) 1239-1251. DOI 10/1016/j.cell.2006.11.033</ref> | In the case of PP2A holoenzyme the <scene name='69/691537/Unitb/1'>B Subunit</scene> (or regulatory subunit) is not part of the core enzyme but rather a coenzyme that associates with the Aα and Cα subunits to form the holoenzyme. This subunit structurally resembles the Aα scaffolding subunit; it contains eighteen alpha helixes stacked antiparallel to each other to cause a crescent structure. Of these eighteen alpha helixes eight of them resemble HEAT repeat motifs that are similar to repeats found on the Aα subunit. These conserved repeats are located on the, largely hydrophobic, convex side of the B subunit. The hydrophobic residues create a groove to which the Aα subunit loosely associates with, mainly via van der Waal interaction. The concave side of the B subunit consists of a variety of negatively charged amino acid residues, which create an isolated acidic environment. The acid nature of the concave side promotes multiple hydrogen bonds with residues from the Cα subunit. These hydrogen bonds coupled with a multitude of van der Waal interactions results in strong B -Cα subunit association. <ref>Xu, Y., Xing, Y., Chen, Y., Chao, Y., Lin, Z., Fan, E., Yu, J.W., Strack, S., Jeffery, P.D., Shi, Y. 2006. Structure of the protein phosphatase 2a holoenzyme. Cell (127) 1239-1251. DOI 10/1016/j.cell.2006.11.033</ref> | ||
