Ubiquinol-cytochrome c reductase iron-sulfur subunit (UQCRFS1), also known as Rieske iron-sulfur protein (RISP), is a component of Complex III in the mitochondrial electron transport chain. UQCRFS1/RISP and two other subunits, cytochrome b (MT-CYB) and cytochrome c1 (CYC1), are essential for the catalytic activity of Complex III. Studies show that UQCRFS1/RISP is required for fetal mouse hematopoietic stem cell differentiation and adult mouse hematopoietic stem cell quiescence. In addition, loss of UQCRFS1/RISP decreases the strength of T cell receptor (TCR) signaling, indicating that this protein is critical for optimal TCR signaling.
