Key biosynthetic enzymes are regulated by their ultimate products through allosteric motions.
through biology and medicine
In these two paintings of ATCase, Geis portrays the structural transformation between the relaxed state (R-state) and tense state (T-state). The two catalytic trimers, illustrated with tiny specks, are seen on the top and bottom, while the three regulatory dimers, depicted with thin bands, are seen on the sides and in the back. Geis utilizes movement and shading techniques to animate the transformation. The arrows on the sides of the paintings show the directions that the enzyme is rotating in each case.
In this painting of ATCase T-state, CTP (represented by a shaded hexagonal ring of cytosine) is shown moving into allosteric binding pockets within the regulatory dimers of the enzyme. Geis utilizes arrows to show the movement of subunits shifting into R-state. A small portion of the third regulatory dimer can be seen in the back of the painting.
In this painting of ATCase R-state, ATP is pictured as a shaded double ring (adenine) binding to the regulatory dimers of the enzyme. Geis illustrates the movement of ATP towards the binding site with a trail of increasing spots. The binding of ATP to ATCase stabilizes the R-state and allows for high affinity substrate-binding.