Ku protein: Difference between revisions

The <scene name='56/567269/Ku_ring/1'>Ku Ring</scene> is composed of a broad base of beta barrels that cradle the DNA, and a narrow bridge that serves to protect the double strand break from base pairing with other DNA base pairs and degradation <ref name="Walker"/>.  There is little interaction between the ring and the backbone or base pairs of DNA; instead, the ring associates with DNA by the cradle fitting into the major grooves of the helix <ref name="Walker"/>.  The positive electrostatic charge caused by polarization of the ring also allows the negatively charged backbone of DNA to be guided into the correct position <ref name="Walker"/> [[NEED SCENE OF POS CHARGE OR POLARIZATION]].  The Ku protein also has a high affinity to DNA due to its form being preset for the helix. As a result of the asymmetric ring, there is a strong preference (Kd value of 1.5 to 4 X 10^-10 M<ref name="Walker"/>) for the <scene name='56/567269/Ku_ring/1'>Ku Ring</scene> to slide onto the ends of DNA <ref name="1"/>.  In addition, other asymmetric features, such as a abundance of Asp residues on the N terminus of the <scene name='56/567269/Ku_heterodimer/3'>Ku heterodimer</scene> [[NEED SCENE OF ASP ON N-TERMINUS OR MAYBE JUST ASP IN GENERAL]],  prevent the Ku protein from sliding further on the DNA helix.  While wrapping over the entire helix, the <scene name='56/567269/Ku_ring/1'>Ku Ring</scene> is thin over the bridge, allowing ligases and polymerases to efficiently interact in [[non-homologous end joining (NHEJ)]]. <ref name="Walker"/>