ABCMdb

PMID: 7515047

Akabas MH, Kaufmann C, Cook TA, Archdeacon P
Amino acid residues lining the chloride channel of the cystic fibrosis transmembrane conductance regulator.
J Biol Chem. 1994 May 27;269(21):14865-8., [PubMed]

Sentences

No. Mutations Sentence Comment

15 ABCC7 p.Arg347Glu ABCC7 p.Lys335Glu ABCC7 p.Lys95Asp Mutation of Lys-95 to Asp, in M1, and Lys-335 and Arg-347 to Glu, in M6, altered the permeability andlor conductance ratios for halides (6). Login to comment 16 ABCC7 p.Arg117His ABCC7 p.Arg334Trp ABCC7 p.Arg347Pro Three mutationsassociated with mild clinical disease, R117H, R334W, and R347P,displayed altered single-channel properties (ll), but the structural basisof the functional changes is unknown. Login to comment 18 ABCC7 p.Arg347His Mutation of Arg-347 to His resulted in theability to eliminate themultiple ion occupancy effects by changing the pH of the intracellular solution, presumablyby titrating the stateof protonation of the histidine. Login to comment 69 ABCC7 p.Lys95Cys ABCC7 p.Gly91Cys ABCC7 p.Gln98Cys Application of the MTS reagents irreversibly alteredthe CFTR-induced currents of three of the cysteine substitution mutants, G91C, K95C, and Q98C. Login to comment 71 ABCC7 p.Gly91Cys 2B and 3A).Application of MTSEA`for 1min irreversibly inhibited the mutants G91C by 43 * 6% (n = 5) (Figs. Login to comment 72 ABCC7 p.Lys95Cys ABCC7 p.Gln98Cys 20 and 3C) and Q98C by 32 2 4% (n= 9) and potentiated the current of the mutant K95C by 108 2 22%(n = 4) (Figs. Login to comment 75 ABCC7 p.Lys95Cys ABCC7 p.Gly91Cys The anionic reagent, MTSES-, had no effect on the K95C and G91C mutants (Fig. 3,A andB).To determine whether thelack of effect was due to inability to react with Cys-95 or lack of effect followingreaction, we sequentially applied MTSES- and MTSEA+;MTSES- did not prevent the potentiationof the current by MTSEA+(data notshown). Login to comment 82 ABCC7 p.Lys95Cys The effect ofthe MTS reagentson wild typeCFTR and on thethreechannel-liningmutants GSlC, K95C,and QSSC. Login to comment 86 ABCC7 p.Lys95Cys ABCC7 p.Gly91Cys ABCC7 p.Gln98Cys A and C are from oocytesinjectedwith wild type CFTR B, Q98C; D,K95C; E, G91C. Login to comment 97 ABCC7 p.Lys95Cys The application ofMTSEA' to the mutant K95C increased the CFTR-induced current. Login to comment 101 ABCC7 p.Lys95Cys ABCC7 p.Lys95Cys 1 MINMTS-EA, 8 MIN C K95C 5 D K95C 5 I -50 0 50 100 150-50 0 50 100 150 CHANGEINCURRENT (X) FIG.3. Login to comment 110 ABCC7 p.Lys95Cys ABCC7 p.Gly91Cys ABCC7 p.Gln98Cys Based on the accessibility of the cysteine-substitution mutants G91C,K95C and Q98C to the MTS reagents, we infer that the side chains of the corresponding wild type residues, Gly-91,Lys-95, and Gln-98, line the channel ofCFTR. Login to comment 122 ABCC7 p.Gly91Arg ABCC7 p.Gly91Cys Although the Arg side chain is somewhat larger than theside chain of Cys modified by MTSEA', the reduction in whole cell current we observed following modification of G91C by MTSEA' suggests that the G91R mutant will have altered single-channel properties. Login to comment 123 ABCC7 p.Lys95Asp Effects on single-channel properties have been observed with other missense mutations associated with mild disease (11).Mutation of Lys-95 to Asp altered the relative anionper- meability sequence of the channel, although no evidence was presented that Lys-95 actually faced the channel lumen (6). Login to comment