ATP synthase is primarily composed of two major structural units: F0 and F1.
F0 Component
- This component is embedded within the membrane (either the inner mitochondrial membrane in eukaryotes, the thylakoid membrane in plants, or the plasma membrane in prokaryotes).
- It acts as a channel for protons (H+) to flow across the membrane, down their electrochemical gradient.
- The flow of protons through F0 drives the rotation of a ring-like structure within it.
F1 Component
- This component protrudes from the membrane and is the catalytic portion of ATP synthase.
- It contains the active sites where ADP and inorganic phosphate (Pi) are combined to form ATP.
- The rotation of the F0 component is mechanically linked to the F1 component, causing conformational changes in the F1 subunits that drive ATP synthesis.
In summary, ATP synthase is a complex molecular machine consisting of the membrane-embedded F0 component, which acts as a proton channel and rotary motor, and the F1 component, which catalyzes the synthesis of ATP.
