SPRIZ (CCDC127) protein conserved in deuterostome animals is a rigid OMM-IMM tether that locally sets mitochondrial IMS volume.

SPRIZ (CCDC127) protein, conserved in deuterostomes, acts as a rigid OMM-IMM tether that sets mitochondrial intermembrane space volume.

• Why it matters: Understanding whether mitochondrial intermembrane volume is genetically specified is crucial for insights into mitochondrial function and signaling.
• What they did: The study identified SPRIZ as an ∼18-nanometer homodimeric tether anchored in the OMM and inserted into the IMM, using cryo-electron tomography, morphometry, and functional assays in mouse liver mitochondria.
• The result: Loss of SPRIZ modestly expanded IMS volume and impaired mitochondrial Ca2+ uptake, indicating that IMS volume is a genetically encoded, tunable architectural parameter shaped by SPRIZ.