scholarly journals Structures and an activation mechanism of human potassium-chloride cotransporters

2020 ◽  
Vol 6 (50) ◽  
pp. eabc5883 ◽  
Author(s):  
Yuan Xie ◽  
Shenghai Chang ◽  
Cheng Zhao ◽  
Feng Wang ◽  
Si Liu ◽  
...  
Keyword(s):  
Potassium Chloride ◽  
Volume Regulation ◽  
Transmembrane Domain ◽  
Cell Volume Regulation ◽  
Full Length ◽  
Aminobutyric Acid ◽  
Activation Mechanism ◽  
Inhibitory Peptide ◽  
Domain Swap ◽  
Functional Studies

Potassium-chloride cotransporters KCC1 to KCC4 mediate the coupled export of potassium and chloride across the plasma membrane and play important roles in cell volume regulation, auditory system function, and γ-aminobutyric acid (GABA) and glycine-mediated inhibitory neurotransmission. Here, we present 2.9- to 3.6-Å resolution structures of full-length human KCC2, KCC3, and KCC4. All three KCCs adopt a similar overall architecture, a domain-swap dimeric assembly, and an inward-facing conformation. The structural and functional studies reveal that one unexpected N-terminal peptide binds at the cytosolic facing cavity and locks KCC2 and KCC4 at an autoinhibition state. The C-terminal domain (CTD) directly interacts with the N-terminal inhibitory peptide, and the relative motions between the CTD and the transmembrane domain (TMD) suggest that CTD regulates KCCs’ activities by adjusting the autoinhibitory effect. These structures provide the first glimpse of full-length structures of KCCs and an autoinhibition mechanism among the amino acid–polyamine-organocation transporter superfamily.

Cryo-EM structures of the human cation-chloride cotransporter KCC1

Science ◽  
2019 ◽  
Vol 366 (6464) ◽  
pp. 505-508 ◽  
Author(s):  
Si Liu ◽  
Shenghai Chang ◽  
Binming Han ◽  
Lingyi Xu ◽  
Mingfeng Zhang ◽  
...  
Keyword(s):  
Ion Transport ◽  
Potassium Chloride ◽  
Volume Regulation ◽  
Cell Volume Regulation ◽  
Aminobutyric Acid ◽  
Computational Studies ◽  
Transport Activity ◽  
Cryo Electron Microscopy ◽  
Cation Chloride Cotransporters ◽  
Functional Analyses

Cation-chloride cotransporters (CCCs) mediate the coupled, electroneutral symport of cations with chloride across the plasma membrane and are vital for cell volume regulation, salt reabsorption in the kidney, and γ-aminobutyric acid (GABA)–mediated modulation in neurons. Here we present cryo–electron microscopy (cryo-EM) structures of human potassium-chloride cotransporter KCC1 in potassium chloride or sodium chloride at 2.9- to 3.5-angstrom resolution. KCC1 exists as a dimer, with both extracellular and transmembrane domains involved in dimerization. The structural and functional analyses, along with computational studies, reveal one potassium site and two chloride sites in KCC1, which are all required for the ion transport activity. KCC1 adopts an inward-facing conformation, with the extracellular gate occluded. The KCC1 structures allow us to model a potential ion transport mechanism in KCCs and provide a blueprint for drug design.

scholarly journals Functional studies of hephaestin in yeast: evidence for multicopper oxidase activity in the endocytic pathway

2003 ◽  
Vol 375 (3) ◽  
pp. 793-798 ◽  
Author(s):  
Liangtao LI ◽  
Chris D. VULPE ◽  
Jerry KAPLAN
Keyword(s):  
Cell Surface ◽  
Oxidase Activity ◽  
Transmembrane Domain ◽  
Multicopper Oxidase ◽  
Full Length ◽  
Endocytic Pathway ◽  
Functional Studies ◽  
Dependent Protein ◽  
A Cell ◽  
Growth Phenotype

Hephaestin is a mammalian gene that encodes a predicted multicopper oxidase required for intestinal iron export. To examine if hephaestin can act as a ferroxidase, we studied yeast strains transformed with plasmids containing both a full-length hephaestin and a hephaestin lacking a transmembrane domain. Yeast with a deletion in FET3, which encodes a cell-surface multicopper oxidase, cannot grow on low-iron media. Expression of full-length hephaestin could complement the low-iron growth phenotype of a Δfet3 strain. Complementation of Δfet3 cells by hephaestin required genes that encode proteins necessary for the copper loading of Fet3p, including CCC2 and GEF1. Expression of hephaestin in Δfet3 cells led to an increase in both iron transport and oxidase activity. These results demonstrate that hephaestin is a copper-dependent protein. In contrast with Fet3p, which is found on the cell surface, hephaestin was co-localized with Pep12p-containing vesicles. Inhibition of endocytosis or deletion of both the vacuolar iron transporters (SMF3 and FET5/FTH1) prevented hephaestin from complementing the low-iron growth phenotype of Δfet3 cells, suggesting that hephaestin is functioning within the endocytic apparatus.

Mechanisms responsible for cell volume regulation during hyperkalemic cardioplegic arrest

2000 ◽  
Vol 70 (2) ◽  
pp. 633-638
Author(s):  
Xiwu Sun ◽  
Christopher T Ducko ◽  
Eric M Hoenicke ◽  
Karen Reigle ◽  
Ralph J Damiano
Keyword(s):  
Cell Volume ◽  
Volume Regulation ◽  
Cell Volume Regulation ◽  
Cardioplegic Arrest
Sign in / Sign up

Export Citation Format

Share Document