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Deduced amino acid sequence and E 1 –E 2 equilibrium of the sarcoplasmic reticulum Ca 2+ ‐ATPase of frog skeletal muscle Comparison with the Ca 2+ ‐ATPase of rabbit fast twitch muscle
Author(s) -
Vilsen Bente,
Andersen Jens Peter
Publication year - 1992
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 - 10.1016/0014-5793(92)81003-5
Subject(s) - endoplasmic reticulum , vanadate , skeletal muscle , atpase , complementary dna , calcium atpase , grenouille , biology , thapsigargin , biochemistry , microbiology and biotechnology , enzyme , rana , chemistry , biophysics , salientia , endocrinology , gene , xenopus
The cDNA encoding a Ca 2+ ‐transport ATPase of frog ( Rana esculenia ) skeletal muscle was isolated and characterized. The deduced amino acid sequence, consisting of 994 residues, showed 89% identity to the fast twitch muscle sarcoplasmic reticulum Ca 2+ ‐ATPases of chicken and rabbit. Northern blot analysis using a fragment of this cDNA as probe detected a 5.0 kb message in frog skeletal muscle but did not detect any mRNA encoding sarcoplasmic reticulum Ca 2+ ‐ATPase in frog cardiac muscle. The enzymatic properties of the amphibian skeletal muscle Ca 2+ ‐ATPase were compared with those of the rabbit fast twitch muscle Ca 2+ ‐ATPase by functional expression of the cDNAs in COS‐1 cells. The amphibian Ca 2+ ‐ATPase displayed a reduced apparent affinity for Ca 2+ and an increased apparent affinity for the inhibitors, vanadate and thapsigargin, relative to the mammalian enzyme. This may be explained by a mechanism in which relatively more of the E 2 conformation accumulated 1 n the frog Ca 2+ ‐ATPase than in the mammalian enzyme.