Research Progress in the Structure and Functions of Prohibitin

Prohibitin is named due to the negative regulatory role of its gene products in cell proliferation. Prohibitin gene is located at q21 of chromosome 17 in human beings and the protein is found at mitochondria, nucleus and cytoplasm. Due to its size and ring-shaped structure, prohibitin protein defines functional subcompartments in mitochondria. Its subunits, PHB1 and PHB2, suppress cell proliferation as in the protein itself. Nevertheless, recent investigation suggests that prohibitin protein enhances cell proliferation as well. It has also been found to suppress cell apoptosis by reducing cytochrome C release via the avoidance of mitochondrial crista remodeling which is facilitated through type 1 optic atrophy protein (OPA1). Acting as a binding site for ubiquitin, prohibitin protein regulates protein degradation by proteasome. Examples are the degradations of sperm mitochondria in a fertilized ovum or those of an abnormal sperm.