Effects of palmitic acid on the binding of insulin 131-I to the rat liver mitochondria.

Effects of palmitic acid, inhibitors, uncouplers, and reduced and oxidized glutathione on the binding of insulin-131! and 131! to the isolated fresh or aged mitochondria were studied. The binding of insulin-1311 to the fresh mitochondria was unexpectedly increased to a greater degree with the exogenous addition of palmitic acid, glutathione, acetaldehyde and 2, 4-dinitrophenol to the medium. The fact indicated that the intactness of mitochondria was not prerequisite for the binding of insulin-1311 to the isolated mitochondria. The binding of insulin-1311 was compared to the fresh mitochondria and the aged mitochondria. Insulin-131 [ bouud to the aged mitochondria in a lesser degree. It is suggested that the binding of insulin-1311 to the mitochondria might be related to the mitochondrial functional and conformational state. The binding of 1311 to the mitochondria was apparently differrnt from that of insulin-1311. And the binding of 1311 was not altered by these uncouplers except in the case of acetaldehyde and ethyl alcohol. This implies that the process of binding of insulin-131! is different from that of 1311. In the case of 1311, it may have some connections with its ion transport mechanism.