Luteinization-specific ovarian mitochondrial proteins

Mitochondria isolated from porcine medium- and large-sized ovarian follicles and corpora lutea show progressive increases in specific proteins temporally associated with luteinization. These include 12-15, 16-17, 33, 47, 50, and 60 kDa proteins. Synthesis of these same mitochondrial proteins is stimulated by incubation of large ovarian follicles with luteinizing hormone (LH) (0.10 microgram/ml) but not by follicle-stimulating hormone (0.10 microgram/ml). A dose-response curve was generated indicating that synthesis of several mitochondrial proteins is stimulated in an LH-dependent manner, while synthesis of two appear to be repressed (70 and 94 kDa). Examination of mitochondrial translation products (cycloheximide-insensitive, chloramphenicol-sensitive protein synthesis) from isolated follicular and luteal mitochondria, by both one- and two-dimensional electrophoresis, demonstrated that two proteins (23 and 35 kDa) are synthesized within luteal but not follicular mitochondria. Further, synthesis of two proteins within follicular mitochondria are significantly reduced in luteal mitochondrial. Regulation of mitochondrial proteins necessary for the rate-limiting step in steroidogenesis is discussed.