Sandbox 154: Difference between revisions

<applet load='1j6z' size='200' color='black' frame='true' align='left' caption='Globular Actin (G-actin): PDB identifier [http://www.rcsb.org/pdb/explore/explore.do?structureId=1J6Z 1J6Z].' scene='Sandbox_154/1j6z_black_true/1'/>

'''G-actin''' is the free monomeric form of actin which polymerizes to F-actin. The structures of globular and filamentous actin are distinct from one another in numerous ways, despite the fact that G-actin comprises F-actin. When the monomeric actin becomes polymerized into F-actin, the unit becomes flattened. Also, F-actin possesses an ATPase function which is minimal in G-actin. G-actin appears to have more <scene name='Sandbox_154/1j6z_calcium/2'>calcium ion</scene> ligands in its structure, external to the active site. Only 3 of the 5 are believed to actually exist in solution and are believed to contribute to the polymerization of G-actin to F-actin<ref name="otterbein">PMID:11474115</ref>. This representation of G-actin also possesses an <scene name='Sandbox_154/1j6z_black_true_dloop/1'>alpha-helical fold in the D-loop</scene> which is observed in some actin crystalline structures but not necessarily<ref name="otterbein"/>. The observed molecule on Cys374, <scene name='Sandbox_154/1j6z_black_true_rho/1'>tetramethylrhodamine-5-maleimide</scene> was used to block polymerization activity so the crystal of G-actin could be observed<ref name="otterbein"/>