ATP-dependent zinc metalloprotease. Plays a role in the formation and regulation of the mitochondrial permeability transition pore (mPTP) and its proteolytic activity is dispensable for this function (PubMed:26387735). Binds 1 zinc ion per subunit. Forms heterooligomers with AFG3L1 and AFG3L2 (By similarity). Component of the mitochondrial permeability transition pore complex (mPTPC), at least composed of SPG7, VDAC1 and PPIF (PubMed:26387735). Interacts with AFG3L2; the interaction is required for the efficient assembly of mitochondrial complex I (PubMed:14623864, PubMed:26387735). Interacts with AFG3L1 (By similarity). Interacts with MAIP1 (PubMed:27499296). Interacts with VDAC1 and PPIF (PubMed:26387735). Ubiquitous. Upon import into the mitochondrion, the N-terminal transit peptide is cleaved by the mitochondrial-processing peptidase (MPP) to generate an intermediate form which undergoes a second proteolytic cleavage mediated by proteases AFG3L1 and/or AFG3L2 removing an additional N-terminal fragment to generate the proteolytically active mature form. The disease is caused by variants affecting the gene represented in this entry. Defects in SPG7 may cause autosomal recessive osteogenesis imperfecta (OI). Osteogenesis imperfecta defines a group of connective tissue disorders characterized by bone fragility and low bone mass. Clinical features of SPG7-related osteogenesis imperfecta include recurrent fractures, mild bone deformities, delayed tooth eruption, normal hearing and white sclera. In the N-terminal section; belongs to the AAA ATPase family. In the C-terminal section; belongs to the peptidase M41 family. A CDS in the 3'-UTR of SPG7 mRNA had been erroneously identified as a cell matrix adhesion regulator and originally thought to be encoded by the CMAR gene. There is no experimental evidence for the production of endogenous CMAR protein. Extended N-terminus. Truncated C-terminus. Paraplegin (SPG7)