Topography of the Leydig cell mitochondrial peripheral-type benzodiazepine receptor.
Native MA-10 mouse Leydig tumor cell mitochondrial preparations were examined by transmission electron (TEM) and atomic force (AFM) microscopic procedures in order to investigate the topography and organization of the peripheral-type benzodiazepine receptor (PBR). Mitochondria were immunolabeled with an anti-PBR antiserum coupled to gold-labeled secondary antibodies. Results obtained indicate that the 18,000 MW PBR protein is organized in clusters of 4-6 molecules. Moreover, on many occasions, the interrelationship among the PBR molecules was found to favor the formation of a single pore. Taking into account recent observations that the 18,000 MW PBR protein is functionally associated with the pore forming 34,000 MW voltage-dependent anion channel (VDAC) these results suggest that (i) the mitochondrial PBR complex could function as a pore, thus allowing the translocation of cholesterol and other molecules to the inner mitochondrial membrane, and (ii) the native receptor is a multimeric complex of an approximate 140,000 MW composed on an average of five 18,000 PBR subunits, one 34,000 VDAC subunit, and associated lipids.
Papadopoulos
V
V
Department of Cell Biology, Georgetown University Medical Center, Washington, DC 20007.
Boujrad
N
N
Ikonomovic
M D
MD
Ferrara
P
P
Vidic
B
B
D000818:Animals; D007150:Immunohistochemistry; D007425:Intracellular Membranes / Q000737:chemistry* / Q000648:ultrastructure; D007984:Leydig Cell Tumor / Q000737:chemistry* / Q000473:pathology* / Q000648:ultrastructure; D007985:Leydig Cells / Q000737:chemistry* / Q000473:pathology* / Q000648:ultrastructure; D008297:Male; D051379:Mice; D018625:Microscopy, Atomic Force; D008854:Microscopy, Electron; D008928:Mitochondria / Q000648:ultrastructure*; D011963:Receptors, GABA-A / Q000032:analysis*; D013736:Testicular Neoplasms / Q000737:chemistry* / Q000473:pathology* / Q000648:ultrastructure; D014407:Tumor Cells, Cultured
D011963:Receptors, GABA-A