However , only complexes I , III , and IV pump protons from the matrix to the intermembrane space ( IMS ) .
Four complexes embedded in the inner membrane of the mitochondrion make up the electron transport chain .
Only complexes I , III , and IV pump protons from the matrix to the intermembrane space ( IMS ) .
Four complexes embedded in the inner membrane of the mitochondrion make up the electron transport chain .