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Both animal and plant cells depend on autophagy in which damaged or superfluous cell material is removed. The degradation of substrates is done by proteins. In animals, it takes place in a cell organelle called the lysosome and in plants and yeasts in the vacuole. Initially, the degradation proteins are not located in the vacuole or lysosome; rather, they must be conveyed by transport receptors on small vesicles to their site of action.
The team at the Biochemistry of Intracellular Transport research group at Ruhr-Universität Bochum (RUB), headed by Dr. Harald Platta, has successfully demonstrated how indispensable the Vps10 transport receptor is for the process.
Study - Researchers - Protein - Vac8 - Fusion
In a second study, the researchers analysed the protein Vac8, which regulates the fusion of small and large vesicles with the vacuole membrane so that the respective load can be released into the interior of the vacuole.
The results were published in June and July 2019 in the Scientific Reports and Cell journals.
Researchers - Transport - Receptor - Vps10 - Plants
The researchers demonstrated that the transport receptor Vps10, which in plants and yeasts directs the degradation protein Pro-Pep4 from the endoplasmic reticulum to the vacuole, is not just one of several exchangeable receptors. "Rather, Vps10 contributes significantly to the activity of the vacuole during the degradation of the cell's own components by effectively transporting Pro-Pep4," says Harald Platta.
Without Vps10, whose counterpart in human cells is called sortilin, Pro-Pep4 can't be efficiently transported to the vacuole and activated to Pep4, which is called cathepsin D in humans.
Degradation - Proteins - Ribosomes - Vacuole - Vps10
While the degradation of the occasional small proteins and ribosomes in the vacuole is still possible without Vps10, it emerged that the degradation of complex substrates, such as peroxisomes or mitochondria, can no longer take place effectively without Vps10 and is associated with a malfunction and thus inefficient maturation of Pro-Pep4.
"The findings from this study are also...
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