Other protrudin-interacting proteins include PDZD8 (a synaptotagmin-like mitochondrial lipid-binding protein), as well as multiple proteins involved with HSP pathogenesis, including myelin proteolipid protein 1, atlastin-1, spastin, REEP1, REEP5, Kif5A-C, and Rtn 1,3, and 4 (Chang et al., 2013; Hashimoto et al., 2014; Elbaz-Alon et al., 2020). The gene discussed is REEP1; the disease is hereditary spastic paraplegia.