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Deletions in the A L region of the h4xb plasma membrane Ca 2+ pump
Author(s) -
de Tezanos Pinto Felicitas,
Adamo Hugo P.
Publication year - 2006
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2006.01.088
Subject(s) - chinese hamster ovary cell , gene isoform , mutant , transmembrane domain , amino acid , alternative splicing , microbiology and biotechnology , hamster , biochemistry , chemistry , enzyme , biology , peptide sequence , biophysics , gene , receptor
Mutants of the plasma membrane Ca 2+ pump (human isoform 4xb) with deletions in the linker between domain A and transmembrane segment M3 (A L region) were constructed and expressed in Chinese hamster ovary cells. The total or partial removal of the amino acid segment 300–349 did not change the maximal Ca 2+ transport activity, but mutants with deletions involving residues 300–338 exhibited a higher apparent affinity for Ca 2+ than the wild type h4xb enzyme. Deletion of the putative acidic lipid interacting sequence (residues 339–349) had no observable functional consequences. The removal of either residues 300–314 or 313–338 resulted in a similar increase in the apparent Ca 2+ affinity of the pump although the increase was somewhat lower than that obtained by the deletion 300–349 suggesting that both deletions affected the same structural determinant. The results show that alterations in the region of the alternative splicing site A change the sensitivity to Ca 2+ of the human isoform 4 of the PMCA.