SUB-MITOCHONDRIAL LOCALIZATION OF THE CATALYTIC SUBUNIT OF PYRUVATE-DEHYDROGENASE PHOSPHATASE

Using a specific antibody against the PDP catalytic subunit, PDPc, pre cise localization of this subunit in mitochondria was performed, Sub-f ractionation of purified mitochondria by controlled swelling processes led to the isolation of outer membranes, matrix space and inner membr ane, vesicles which were purified on a sucrose density gradient, In th is study, me demonstrated that PDPc was not recovered as a soluble pro tein in the matrix space but was associated with the inner membrane, M oreover, Triton X-114 phase partitioning performed on inner membranes showed that PDPc behaved both as a hydrophilic and as a hydrophobic pr otein, thus suggesting two different forms of this enzyme.