The ATP Synthase, H+ Transporting, Mitochondrial F1 Complex, O Subunit encoded by ATP5O is a component of the F-type ATPase found in the mitochondrial matrix. F-type ATPases are composed of a catalytic core and a membrane proton channel. The encoded protein appears to be part of the connector linking these two components and may be involved in transmission of conformational changes or proton conductance.