PGRMC2 (progesterone receptor membrane component 2) serves as a critical intracellular heme chaperone and metabolic regulator with diverse physiological functions. PGRMC2 is required for delivery of labile, or signaling heme, from mitochondria to the nucleus, where it regulates heme-responsive transcriptional repressors such as Rev-Erbα and BACH1 1. This heme transport function is particularly important in brown adipose tissue, which has high heme demands for thermogenesis 1. PGRMC2 plays essential roles in adipocyte function and systemic glucose homeostasis, with deletion causing severe mitochondrial defects and impaired adaptive thermogenesis 1. In reproductive tissues, PGRMC2 acts as a non-classical progesterone receptor, showing cyclic expression patterns in human endometrium and being essential for decidualization and embryo implantation 2. PGRMC2 forms functional complexes with other progesterone mediators like PGRMC1 and PAQR7 to regulate cell cycle progression 3. In cardiac tissue, PGRMC2 serves as a pressure-volume regulator maintaining normal cardiac contractility and output, particularly under hypoxic stress conditions 4. The protein also contributes to immune homeostasis at maternal-fetal interfaces 5 and appears to promote tumor growth in reproductive cancers, making it a potential therapeutic target 6.