Abstract:
:The mitochondrial channel, VDAC, forms large (3 nm in diameter) aqueous pores through membranes. We measured ATP flow (using the luciferin/luciferase method) through these channels after reconstitution into planar phospholipid membranes. In the open state of VDAC, as many as 2 x 10(6) ATP molecules can flow through one channel per second. The half-maximum rate occurs at approximately 75 mM ATP. The permeability of a single channel for ATP is 1.1 x 10(-14) cm3/s (about 1 cm/s after correcting for cross-sectional area), which is 100 times less than the permeability for chloride and 10 times less than that for succinate. Channel closure results in a 50% reduction in conductance, showing that monovalent ions are still quite permeable, yet ATP flux is almost totally blocked. This is consistent with an electrostatic barrier that results in inversion of the selectivity of the channel and could be an example of how large channels selectively control the flow of charged metabolites. Thus VDAC is ideally suited to controlling the flow of ATP between the cytosol and the mitochondrial spaces.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Rostovtseva T,Colombini Mdoi
10.1016/S0006-3495(97)78841-6subject
Has Abstractpub_date
1997-05-01 00:00:00pages
1954-62issue
5eissn
0006-3495issn
1542-0086pii
S0006-3495(97)78841-6journal_volume
72pub_type
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