Complex I is the largest protein complex of the oxidative phosphorylation system in mitochondrial and it catalyzes NADH-quinone oxidoreduction. Complex I represents the main entrance site for electrons into the respiratory electron transfer chain. In Arabidopsis, Complex I have at least 49 subunits and PSST (AT5G11770) is one of the subunit, which is also designated 20 kDa subunit.
