Triggering of mannosyltransferase activity in inner mitochondrial membranes by dolichyl‐monophosphate incorporation mediated through phospholipids or fatty acids

The activity of GDPmannose: dolichyl monophosphate mannosyltransferase in inner mitochondrial mem‐branes can be triggered by dolichyl‐monophosphate incorporation mediated through phospholipids or fatty acids. The efficiency of this incorporation and the efficiency of the enzyme activity are not equivalent. Among a variety of amphiphiles which were tested, the highest mannosyltransferase activity was obtained with the mixture of lipids extracted from the outer mitochondrial membranes. The results presented here appear consistent only with a mechanism involving collisional contacts of the phospholipid vesicles and fusion with the membranes. ESR spectroscopy confirms that (a) the incorporation process is followed by solubilization of dolichyl monophosphate molecules in the lipid phase and (b) the general organization of the inner mitochondrial membranes is not perturbed by the addition of dolichyl monophosphate.