ABCMdb

PMID: 12763779

Corre F, Jaxel C, Fuentes J, Menguy T, Falson P, Levine BA, Moller JV, le Maire M
Involvement of the cytoplasmic loop L6-7 in the entry mechanism for transport of Ca2+ through the sarcoplasmic reticulum Ca2+-ATPase.
Ann N Y Acad Sci. 2003 Apr;986:90-5., [PubMed]

Sentences

No. Mutations Sentence Comment

6 ABCC8 p.Asp818Ala Bioquímica y Biología Molecular y Genética, E.U. Enfermería y T.O., Universidad de Extremadura, Cáceres, Spain cSchool of Biosciences, University of Birmingham, B15 2TT United Kingdom dDepartment of Biophysics, University of Aarhus, DK-8000 Aarhus C, Denmark ABSTRACT: We have found that despite a markedly low calcium affinity the D813A/D818A mutant is capable, after complexation with Cr.ATP, of occluding Ca2+ to the same extent (1-2 Ca2+ per ATPase monomer) as wild-type ATPase. Login to comment 13 ABCC8 p.Asp818Ala ABCC8 p.Asp818Ala lemairem@dsvidf.cea.fr part of the L6-7 loop (p808-818) interacted with Ca2+.1 Cluster mutation Ca2+- ATPase constructs, D813A-D818A (later called ADA) and D813A-D815A-D818A, displayed a marked reduction in the apparent affinity with which Ca2+ controls ATPase phosphorylation and turnover.2,3 We have rationalized our findings in terms of involvement of the conserved aspartic residues of the L6-7 loop in the interaction with calcium ions during the initial steps of the Ca2+ binding process.4 The crystal structures of SERCA 1a,5,6 however, show the acidic residues of the L6-7 loop in a conformation unsuitable for multiple coordination by Ca2+. Login to comment 20 ABCC8 p.Asp818Ala Solubilization by C12E8 of Various Cr.ATP-reacted Ca2+-ATPase Species as a Function of Calcium In similar experiments we found that, as previously reported,7 the E309Q mutant does not occlude Ca2+, but several attempts to measure Cr.ATP-induced Ca2+ occlusion by the E771Q (previously also reported to display no calcium occlusion7) and the D813A-D815A-D818A mutants failed, because we were unable to recover any Ca2+-ATPase after elution from the HPLC column. Login to comment