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Prostasin interacts with the epithelial Na+ channel and facilitates cleavage of the γ-subunit by a second protease.
- Source :
-
American Journal of Physiology: Renal Physiology . 11/1/2014, Vol. 307 Issue 9, pF1080-F1087. 8p. - Publication Year :
- 2014
-
Abstract
- During maturation, the α- and γ-subunits of the epithelial Na+ channel (ENaC) undergo proteolytic processing by furin. Cleavage of the γ-subunit by furin at the consensus site γRKRR143 and subsequent cleavage by a second protease at a distal site strongly activate the channel. For example, coexpression of prostasin with ENaC increases both channel function and cleavage at the γRKRK186 site. We generated a polyclonal antibody that recognizes the region 144-186 in the γ-subunit (anti-γ43) to determine whether prostasin promotes the release of the intervening tract between the putative furin and γRKRK186 cleavage sites. Anti-γ43 precipitated both full-length (93 kDa) and furin-processed (83 kDa) γ-subunits from extracts obtained from oocytes expressing αβHA-γ-V5 channels, but only the fulllength (93 kDa) γ-subunit from oocytes expressing αβHA-γ-V5 channels and either wild-type or a catalytically inactive prostasin. Although both wild-type and catalytically inactive prostasin activated ENaCs in an aprotinin-sensitive manner, only wild-type prostasin bound to aprotinin beads, suggesting that catalytically inactive prostasin facilitates the cleavage of the γ-subunit by an endogenous protease in Xenopus oocytes. As dietary salt restriction increases cleavage of the renal γ-subunit, we assessed release of the 43-mer inhibitory tract on rats fed a low-Na+ diet. We found that a low-Na+ diet increased γ-subunit cleavage detected with the anti-γ antibody and dramatically reduced the fraction precipitated with the anti-γ43 antibody. Our results suggest that the inhibitory tract dissociates from the γ-subunit in kidneys from rats on a low-Na+ diet. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 1931857X
- Volume :
- 307
- Issue :
- 9
- Database :
- Academic Search Index
- Journal :
- American Journal of Physiology: Renal Physiology
- Publication Type :
- Academic Journal
- Accession number :
- 99361611
- Full Text :
- https://doi.org/10.1152/ajprenal.00157.2014