Deduced amino acid sequence and E1-E2 equilibrium of the sarcoplasmic reticulum Ca(2+)-ATPase of frog skeletal muscle. Comparison with the Ca(2+)-ATPase of rabbit fast twitch muscle.
The cDNA encoding a Ca(2+)-transport ATPase of frog (Rana esculenta) 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 Ca2+ 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 E2 conformation accumulated in the frog Ca(2+)-ATPase than in the mammalian enzyme.
Vilsen
B
B
Danish Biomembrane Research Centre, University of Aarhus, Denmark.
Andersen
J P
JP
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004247:DNA; D008969:Molecular Sequence Data; D009132:Muscles / Q000201:enzymology*; D010766:Phosphorylation; D011817:Rabbits; D011893:Rana esculenta; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D016415:Sequence Alignment; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D014638:Vanadates / Q000494:pharmacology
D013729:Terpenes; D014638:Vanadates; D019284:Thapsigargin; D004247:DNA; D000252:Calcium-Transporting ATPases; D002118:Calcium