User:Alice Harmon/Sandbox 1: Difference between revisions

To get an idea of the structural differences that occur during a catalytic cycle and in in active and inactive enzymes, use the links below to compare active PKA in complex with ANP and PKI [[1atp]] (the same structure used above), active apo PKA [[1j3h]], and inactive, unphosphorylated PKA [[4dfy]] (activation loop threonine is not phosphorylated), shown in the left, middle, and right frames, respectively. 1atp and 1j3h show the closed and open structures assumed by PKA in the catalytic cycle. 4dfy shows the structure of an inactive form of PKA, in which the internal structure is disorganized due to the lack of phosphorylation of threonine 197 in the activation loop. Phosphorylation is required for formation of hydrogen bonds that are critical for alignment of structures to form the active site. Note that some residues in 1j3h and 4dfy are not depicted in the models because they are disordered and not resolved in the structures. Click on all three links with same number to compare the indicated features. Legends for each set of scenes are below. To reset the structures, reload the page.