ABCMdb

PMID: 18996847

Garneau L, Klein H, Banderali U, Longpre-Lauzon A, Parent L, Sauve R
Hydrophobic interactions as key determinants to the KCa3.1 channel closed configuration. An analysis of KCa3.1 mutants constitutively active in zero Ca2+.
J Biol Chem. 2009 Jan 2;284(1):389-403. Epub 2008 Nov 7., [PubMed]

Sentences

No. Mutations Sentence Comment

110 ABCC8 p.Ala286Gly Results obtained with the V275C/A286G mutant are also included to illustrate the effect of MTSEAϩ on a nonconstitutively active channel, despite Ala286 facing the channel pore. Login to comment 119 ABCC8 p.Ala286Gly D, constitutive activation was not seen with the V275C/A286G mutant, although Ala286 is facing the channel pore just like Ala279 and Val282 . Login to comment 123 ABCC8 p.Ala286Gly ABCC8 p.Ala286Gly The continuous application of MTSEAϩ onto the V275C/A286G mutant in Ca2ϩ free conditions (Fig. 5D) did not result in a detectable current inhibition (I0 ϭ IEGTA) confirming that V275C/A286G is not constitutively active. Login to comment 124 ABCC8 p.Ala286Gly Furthermore, the absence of inhibition in this case cannot be attributed to cysteines at position 275 not being accessible to MTSEAϩ for the V275C/A286G mutant, because the subsequent addition of Ca2ϩ failed to initiate current activation, thus indicating covalent modification of V275C. Login to comment 212 ABCC8 p.Ala286Gly ABCC8 p.Ala286Gly D, an identical perfusion protocol applied to the V275C/A286G mutant failed to provide evidence of an MTSEAϩ -induced inhibition of I0, in accordance with V275C/A286G being closed in the absence of Ca2ϩ . Login to comment 305 ABCC8 p.Ala286Cys ABCC8 p.Ala286Cys In addition, although binding of MTSETϩ to Cys engineered at 286 led to channels with an increased sensitivity to Ca2ϩ , neither the A286C nor the A286C mutants modified by MTSETϩ showed constitutive activity as shown previously (13). Login to comment 378 ABCC8 p.Ala286Cys These additional gating mechanisms might explain Po values of the order of 0.2 at saturating Ca2ϩ concentrations (beta1 Ͼ ␣1) reported for the wild type KCa3.1 (46) as well as the drastic Po increase of the A283C and A286C mutants following binding of MTSEAϩ (13, 20). Login to comment