Binding of GlyH-101 in the Pore of the CFTR Chloride Channel

Abstract

with thirty-five deubiquitylase enzymes, we identified Usp8 as the specific DUB involved in deubiquitination of the endocytosed KCa3.1. This result was confirmed in HEK cells, by measuring membrane KCa3.1 ubiquitination and degradation rate in the presence of the wild type or catalytically inactive mutant of Usp8. Thus, overexpression of wild type Usp8 accelerates channel deubiquitination, while the mutant Usp8 strongly enhanced accumulation of ubiquitinated KCa3.1. Interestingly, in both cases the rate of channel degradation was delayed. In conclusion, we demonstrate that poly-ubiquitination mediates the targeting of membrane KCa3.1 to the lysosomes and also that Usp8 regulates the rate of KCa3.1 degradation by deubiquitinating KCa3.1 before delivery to lysosomes.