Mutations in the OPA1 gene are associated with autosomal dominant optic atrophy. 
OPA1 encodes a dynamin-related protein orthologous to Msp1 of 
Schizosaccharomyces pombe and Mgm1p of Saccharomyces cerevisiae, both involved 
in mitochondrial morphology and genome maintenance. We present 
immuno-fluorescence and biochemical evidences showing that OPA1 resides in the 
mitochondria where it is imported through its highly basic amino-terminal 
extension. Proteolysis experiments indicate that OPA1 is present in the 
inter-membrane space and electron microscopy further localizes it close to the 
cristae. The strong association of OPA1 with membranes suggests its anchoring to 
the inner membrane.