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Procaspase-9 is attached to the mitochondrial outer membrane in the early stages of apoptosis

Cellular & Molecular Biology LettersAn International Journal200712:20

Received: 31 January 2007

Accepted: 2 March 2007

Published: 28 April 2007


Procaspase-9 is the zymogen form of one of the apoptosis initiators, caspase-9. Its cellular location may differ depending on the cell type; it is found throughout the cytosol, although some of it may be associated with the mitochondria. Procaspase-9 relocates from the cytosol to the mitochondria shortly after the triggering of apoptosis in rat hepatocytes. We investigated whether the mitochondrial protein import machineries import procaspase-9. The combined results of protein import analyses, mitochondrial fractionation and protease treatments of intact and swollen mitochondria imply that procaspase-9 attaches to the outer surface of the mitochondrial outer membrane.

Key words

Caspase-9Procaspase-9MitochondriaApoptosisProtein importRotenoneLocalization