Logo image
Back
The Two Nucleotide-binding Domains of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Have Distinct Functions in Controlling Channel Activity
Journal article   Open access   Peer reviewed

The Two Nucleotide-binding Domains of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Have Distinct Functions in Controlling Channel Activity

Mark R Carson, Sue M Travis and Michael J Welsh
The Journal of biological chemistry, Vol.270(4), pp.1711-1717
01/27/1995
DOI: 10.1074/jbc.270.4.1711
PMID: 7530246
url
https://doi.org/10.1074/jbc.270.4.1711View
Published (Version of record) Open Access

Abstract

The cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel contains two cytoplasmic nucleotide-binding domains (NBDs). After phosphorylation of the R domain, ATP interacts with the NBDs to regulate channel activity. To learn how the NBDs regulate channel function, we used the patch-clamp technique to study CFTR and variants which contained site-directed mutations in the conserved Walker A motif lysine residues in either NBD1 (K464A), NBD2 (K1250A and K1250M), or both NBDs simultaneously (K464A/K1250A). Studies in related proteins suggest that such mutations slow the rate of ATP hydrolysis. These mutations did not alter the conductive properties of the channel or the requirement for phosphorylation and ATP to open the channel. However, all mutations decreased open state probability. Mutations in NBD1 decreased the frequency of bursts of activity, whereas mutations in NBD2 and mutations in both NBDs simultaneously prolonged bursts of activity, as well as decreased the frequency of bursts. These results could not be attributed to altered binding of nucleotide because none of the mutants studied had reduced 8-N3ATP binding. These data suggest that the two NBDs have distinct functions in channel gating; ATP hydrolysis at NBD1 initiates a burst of activity, and hydrolysis at NBD2 terminates a burst.

Details

Metrics

14 Record Views
235 Times Cited - Web of Science
Logo image