ABCMdb

PMID: 9724537

Akabas MH
Channel-lining residues in the M3 membrane-spanning segment of the cystic fibrosis transmembrane conductance regulator.
Biochemistry. 1998 Sep 1;37(35):12233-40., 1998-09-01 [PubMed]

Sentences

No. Mutations Sentence Comment

97 ABCC7 p.Leu211Cys All of the mutants expressed cAMP-activated currents in FIGURE 2: MTS reagents do not inhibit currents induced by wild-type CFTR but they do inhibit currents induced by the L211C mutant. Login to comment 98 ABCC7 p.Leu211Cys Normalized current at -100 mV recorded from individual oocytes expressing wild-type CFTR (A and C) and the L211C mutant (B and D). Login to comment 105 ABCC7 p.Ala198Cys ABCC7 p.Pro205Cys The baseline conductance of the oocytes was generally less than 2.5 µS. The average cAMP-stimulated CFTR conductance for the cysteine-substitution mutants ranged between 49 µS for P205C and 142 µS for the A198C mutant (Figure 3A); for wild type the average conductance was 108 µS. The cAMP-stimulated current reached a plateau within 22 min in oocytes expressing wild-type CFTR. Login to comment 106 ABCC7 p.Ile203Cys ABCC7 p.Leu197Cys For the cysteine-substitution mutants the time to reach the plateau ranged from 19 min for the L197C mutant to 57 min for the I203C mutant (Figure 3B). Login to comment 107 ABCC7 p.Glu193Cys ABCC7 p.Asp192Cys It is interesting to note that all of the cysteine-substitution mutants that were not affected by the MTS reagents except D192C and E193C reached the plateau current in less than 30 min. Login to comment 113 ABCC7 p.Leu211Cys ABCC7 p.Pro205Cys ABCC7 p.Ile203Cys ABCC7 p.Phe200Cys ABCC7 p.Gln207Cys ABCC7 p.His199Cys ABCC7 p.Trp202Cys In contrast, a 1-min application of 10 mM MTSES- significantly inhibited the CFTR-induced currents for the mutants H199C, F200C, W202C, I203C, P205C, Q207C, and L211C (Figure 4). Login to comment 119 ABCC7 p.Leu214Cys In addition, a 1-min application of 2.5 mM MTSEA+ also inhibited the mutant L214C (Figure 5). Login to comment 167 ABCC7 p.His199Cys Thus, in order for the MTS reagents to reach the most cytoplasmic accessible residue in the M3 segment, H199C, the channel must be at least 6 Å in diameter from the extracellular end to the level of His199. Login to comment 200 ABCC7 p.Pro205Ser The mutation P205S is associated with mild CF (58); this and other mutations of Pro205 reduce the formation of mature CFTR protein but they do not alter the halide permeability and conductance ratios (31). Login to comment 222 ABCC7 p.Pro205Ser ABCC7 p.Leu206Trp ABCC7 p.His199Tyr ABCC7 p.Glu193Lys ABCC7 p.Asp192Gly Several mutations of residues in and flanking the M3 membrane-spanning segment have been identified in patients with CF, including D192G, E193K, H199Y, P205S, and L206W (58, 60-63). Login to comment