A new member of the dynamin GTPase family (OPA1) was recently identified in 
humans and shown to be mutated in patients with dominant optic atrophy. To 
understand better the function of mammalian OPA1, we isolated a mouse ortholog 
(mOPA1) from brain and raised a specific antibody against its C terminus. The 
subcellular distribution of mOPA1 overexpressed in COS-7 cells largely 
overlapped that of endogenous cytochrome c, a well known mitochondrial marker, 
and dramatically affected mitochondrial morphology, altering it from tubular to 
vesicular. Mitochondrial targeting was mediated by the N-terminal region of 
mOPA1 as follows: deletion of the 124 N-terminal amino acids eliminated 
mitochondrial targeting, although fusion of the N-terminal 60 or 90 amino acids 
of mOPA1 with green fluorescent protein resulted in its mitochondrial targeting. 
mOPA1 was expressed widely in the mouse brain, especially in neurons of 
olfactory bulb, cerebral cortex, piriform cortex, hypothalamus, hippocampus, red 
nucleus, cochlear nucleus, motor trigeminal nucleus, facial nucleus, cerebellar 
nucleus, and Purkinje cells. Within dissociated cerebellar cells, mOPA1 protein 
was clearly observed in the dendrites and somas of neuronal cells, as well as in 
astrocytes and meningeal cells. In each case, it was distributed in the 
vesicular pattern seen in other cell types.