What is the primary function of cardiolipin in cell membranes?

Cardiolipin primarily functions to enhance the structure and stability of the inner mitochondrial membrane, playing a critical role in cellular energy metabolism. It is a unique phospholipid that contributes significantly to the formation of protein complexes involved in the electron transport chain, which is essential for ATP production. By anchoring and organizing these protein complexes, cardiolipin facilitates efficient energy conversion processes within mitochondria.

In the context of cell membranes, cardiolipin does not typically act as a barrier to toxins, facilitate nutrient transport, or enhance membrane fluidity in the same manner as other phospholipids might. Instead, its principal role is more about the structural integrity and functional organization of specific membrane domains, especially within mitochondria, where it ensures optimal conditions for the proteins involved in oxidative phosphorylation.