A leucine motif in the amino acid sequence of subunit 9 of the mitochondrial ATPase, and other hydrophobic membrane proteins, that is highly conserved by editing.

Subunit 9 of the mitochondrial ATPase, but also other hydrophobic mitochondrially encoded proteins, contains a high frequency of the leucine motif, -Leu-X9-Leu-, which is highly conserved through RNA editing. The leucine motif may provide specific recognition sites between membrane-spanning domains of the F0-ATPase and between other hydrophobic subunits during the assembly of multienzyme complexes in the inner mitochondrial membrane.