The cytosolic chaperonin TRiC was isolated from ovine testes using ultracentrifugation and heparin-Sepharose chromatography. The molecular mass of the obtained preparation was shown to exceed 900 kDa (by Blue Native PAGE). SDS-PAGE yielded a set of bands in the range of 50-60 kDa. Electron microscopy examination revealed ring-shaped complexes with the outer diameter of 15 nm and the inner diameter of approximately 6 nm. The results suggest that the purified chaperonin is an oligomeric complex composed of two 8-membered rings. The chaperonin TRiC was shown to assist an ATP-dependent refolding of recombinant forms of sperm-specific glyceraldehyde-3-phosphate dehydrogenase, an enzyme that is expressed only in precursor cells of the sperms in the seminiferous tubules of the testes. In contrast, TRiC did not influence the refolding of muscle isoform of glyceraldehyde-3-phosphate dehydrogenase and assisted the refolding of muscle lactate dehydrogenase by an ATP-independent mechanism. The obtained results suggest that TRiC is likely to be involved in the refolding of sperm-specific proteins.
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The ring-shaped chaperonin T-complex protein ring complex (TRiC; also known as chaperonin containing TCP-1, CCT) is an ATP-driven protein-folding machine that is essential for maintenance of cellular homeostasis. Its dysfunction is related to cancer and neurodegenerative disease. Despite its importance, how TRiC works in the cell remains unclear.
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Guangdong Provincial Key Laboratory of Autophagy and Major Chronic Non-communicable Diseases, Key Laboratory of Prevention and Management of Chronic Kidney Diseases of Zhanjiang City, Institute of Nephrology, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China.
Protein aggregation, a defining characteristic of numerous human diseases, poses a significant challenge to cellular health. Autophagy, an essential cellular recycling process, specifically targets and degrades these harmful protein aggregates through a specialized mechanism known as aggrephagy. However, the precise mechanisms underlying the exquisite selectivity of aggrephagy in identifying and eliminating only aggregated proteins while sparing healthy cellular components have remained enigmatic.
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