Conserved extracellular cysteine residues in the inwardly rectifying potassium channel Kir2.3 are required for function but not expression in the membrane
Jpa. Bannister et al., Conserved extracellular cysteine residues in the inwardly rectifying potassium channel Kir2.3 are required for function but not expression in the membrane, FEBS LETTER, 458(3), 1999, pp. 393-399
The mouse potassium channel Kir2,3 possesses conserved extracellular cystei
ne residues at positions 113 and 145, We have investigated the role of thes
e cysteines in structure/function and membrane trafficking. Cysteine to ser
ine mutations resulted in the absence of potassium currents in oocytes and
coexpression of these mutants with wild-type channel showed a dominant nega
tive inhibition of wild-type currents. FLAG-tagged channels expressed in oo
cytes were detected in the cell membrane by anti-FLAG antibody for wild-typ
e and mutant channels, In vitro translation using the reticulocyte lysate s
ystem showed that mutation of these residues did not affect processing nor
insertion into membranes. Cysteine residues at 113 and 145 are therefore re
quired for function of the Kir2,3 channel but not for processing into the c
ell membrane; disulfide bonds between subunits are unlikely. (C) 1999 Feder
ation of European Biochemical Societies.