TY - JOUR
T1 - Subcellular localization of human voltage-dependent anion channel isoforms
AU - Yu, Wei Hong
AU - Wolfgang, William
AU - Forte, Michael
PY - 1995/6/9
Y1 - 1995/6/9
N2 - The voltage-dependent anion channel of the outer mitochondrial membrane, VDAC (also known as mitochondrial porin), is a small abundant protein which forms a voltage-gated pore when incorporated into planar lipid bilayers. This protein forms the primary pathway for movement of major metabolites through the outer membrane. Recently, it has been demonstrated that two human VDAC genes, HVDAC1 and HVDAC2, produce three proteins that differ most significantly at their amino termini. These results suggest that the distinct amino termini lead to the targeting of individual VDAC isoforms to different cellular compartments. Consistent with this hypothesis, recent reports suggest that HVDAC1 is found in the plasma membrane of mammalian cells. To define the subcellular location of HVDAC isoforms, HVDAC genes were modified so that the encoded proteins contain COOH-terminal epitopes recognized by either of two monoclonal antibodies. Introduction of these epitope tags had no effect on the function of modified VDAC proteins. Epitope-tagged proteins were then individually expressed in COS7 cells or rat astrocytes and the intracellular location of each isoform subsequently identified by subcellular fractionation, light level immunofluorescence, and immunoelectron microscopy. Our results demonstrate that each HVDAC protein is exclusively located in fractions or subcellular regions containing mitochondrial marker proteins. In addition, immunofluorescence and immunoelectron microscopy show that an individual mitochondrion can contain both HVDAC1 and HVDAC2. Our results call into question previous reports demonstrating VDAC molecules in the plasma membrane and suggest that functional differences between individual VDAC isoforms may result in distinct regulatory processes within a single mitochondrion.
AB - The voltage-dependent anion channel of the outer mitochondrial membrane, VDAC (also known as mitochondrial porin), is a small abundant protein which forms a voltage-gated pore when incorporated into planar lipid bilayers. This protein forms the primary pathway for movement of major metabolites through the outer membrane. Recently, it has been demonstrated that two human VDAC genes, HVDAC1 and HVDAC2, produce three proteins that differ most significantly at their amino termini. These results suggest that the distinct amino termini lead to the targeting of individual VDAC isoforms to different cellular compartments. Consistent with this hypothesis, recent reports suggest that HVDAC1 is found in the plasma membrane of mammalian cells. To define the subcellular location of HVDAC isoforms, HVDAC genes were modified so that the encoded proteins contain COOH-terminal epitopes recognized by either of two monoclonal antibodies. Introduction of these epitope tags had no effect on the function of modified VDAC proteins. Epitope-tagged proteins were then individually expressed in COS7 cells or rat astrocytes and the intracellular location of each isoform subsequently identified by subcellular fractionation, light level immunofluorescence, and immunoelectron microscopy. Our results demonstrate that each HVDAC protein is exclusively located in fractions or subcellular regions containing mitochondrial marker proteins. In addition, immunofluorescence and immunoelectron microscopy show that an individual mitochondrion can contain both HVDAC1 and HVDAC2. Our results call into question previous reports demonstrating VDAC molecules in the plasma membrane and suggest that functional differences between individual VDAC isoforms may result in distinct regulatory processes within a single mitochondrion.
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U2 - 10.1074/jbc.270.23.13998
DO - 10.1074/jbc.270.23.13998
M3 - Article
C2 - 7539795
AN - SCOPUS:0029040549
SN - 0021-9258
VL - 270
SP - 13998
EP - 14006
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 23
ER -