Figure 24.5 
Structures of phosphorylase a and phosphorylase b. Phosphorylase a is phosphorylated on serine 14 of each subunit. This modification favors the structure of the more active R state. One subunit is shown in white, with helices and loops important for regulation shown in blue and red. The other subunit is shown in yellow, with the regulatory structures shown in orange and green. phosphorylase b is not phosphorylated and exists predominantly in the T state. Notice that the catalytic sites are partly occluded in the T state.
Structures of phosphorylase a and phosphorylase b. Phosphorylase a is phosphorylated on serine 14 of each subunit. This modification favors the structure of the more active R state. One subunit is shown in white, with helices and loops important for regulation shown in blue and red. The other subunit is shown in yellow, with the regulatory structures shown in orange and green. phosphorylase b is not phosphorylated and exists predominantly in the T state. Notice that the catalytic sites are partly occluded in the T state.