Purification and Characterisation of a Pore Protein of the Outer Mitochondrial Membrane from Neurospora crassa

The major protein of the outer mitochondrial membrane of Neurospora
was purified. On dodecylsulfate-containing gels it displayed a
single bend with an apparent molecular weight of 31000.
reconstitution experiments with artifical lipid bilayers showed
that this protein forms pores. Pore conductance was dependent on
the voltage across the membrane. The protein inserted into the
membrane in an oriented fashion, the membrane current being
dependent on the sign of the voltage. Single pore conductance was
5nS, suggesting a diameter of 2nm of the open pore. This
mitochondrial protein shows a number of similarities to the outer
membrane porins of gram-negative bacteria.