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Updated: Jul 3, 2026

Cycloheximide Chase Analysis of Protein Degradation in Saccharomyces cerevisiae
Published on: April 18, 2016
Ubiquitin ligase Kf-1 is involved in the endoplasmic reticulum-associated degradation pathway
Yoshiaki Maruyama1, Misa Yamada, Kou Takahashi
1Department of Psychogeriatrics, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi, Kodaira, Tokyo 187-8553, Japan.
Abstract:
Kf-1 was first identified as a gene showing enhanced expression in the cerebral cortex of a sporadic Alzheimer's disease patient. To date, however, the functional properties of Kf-1 protein remain unknown. In this study, immunohistochemical analysis showed that Kf-1 immunoreactivity was detected in rat hippocampus and cerebral cortex neurons. Interestingly, it was colocalized with endoplasmic reticulum (ER) marker. To investigate the specific function of Kf-1 protein, we generated Myc tagged wild type Kf-1 (Myc-Kf-1WT) and RING finger domain deletion mutant of Kf-1 (Myc-Kf-1DeltaR), and then transfected in HEK293 cells. Myc-Kf-1WT displayed a reticular pattern typical of ER localization, with large perinuclear aggregates and colocalized with ER marker, calnexin. Myc-Kf-1WT facilitated ubiquitination of endogenous proteins, whereas Myc-Kf-1DeltaR did not show ubiquitin ligase activity. In addition, we found that Kf-1 interacted with components of the ER-associated degradation (ERAD) pathway, including Derlin-1 and VCP. Taken together, these properties suggest that Kf-1 is an ER ubiquitin ligase involved in the ERAD pathway.
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