Malonyl-CoA binding site and the overt carnitine palmitoyltransferase activity reside on the opposite sides of the outer mitochondrial membrane.

These findings show that whereas the malonyl-CoA binding site relevant to the inhibition of carnitine palmitoyltransferase is situated on the outer side of the outer membrane, the overt carnitine palmitoyltransferase activity resides on the inner side of the outer membrane

M S Murthy; S V Pande

2006

Scholarcy highlights

  • The overt carnitine palmitoyltransferase activity of intact mitochondria from rat heart and liver was found to be resistant to the action of proteases such as Nagarse
  • These findings show that whereas the malonyl-CoA binding site relevant to the inhibition of carnitine palmitoyltransferase is situated on the outer side of the outer membrane, the overt carnitine palmitoyltransferase activity resides on the inner side of the outer membrane
  • The data of this report clearly show that the malonyl-CoAinhibitable overt CPT activity resides in the Outer Membrane and not in the inner membrane
  • Malonyl-CoA sensitivity of carnitine palmitoyltransferase in the OM fraction was the same as in intact mitochondria, and it is known that the CPTj is not malonyl-CoA inhibitable
  • A consideration of why in earlier studies the CPTO was concluded to reside in the IM is in order
  • The possibility that CPTO, which constituted a small fraction of the total CPT activity, might reside elsewhere in mitochondria, in the OM, was missed, Norum et al had recognized that their results did not completely rule out the possibility of some CPT being present in the OM
  • Tetradecylglycidyl-CoA with 70 ,M palmitoyl-CoA present; other details as in Table 2) was not affected by Nagarse, indicating that tetradecylglycidyl-CoA inhibits carnitine palmitoyltransferase activity by binding to the catalytic site

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