REEP1 and hereditary spastic paraplegia: By contrast, REEP1 ubiquitination was preserved in the missense variants P19L and T55K, which are associated with pure HSP.[57, 58] To confirm these findings, we cotransfected HEK‐293T cells with constructs either encoding the WT or the variant REEP1 protein together with His6–ubiquitin.