title: Crystal structure of sarcoplasmic reticulum Ca2+-ATPase (SERCA) from bovine muscle.
abstract: The SERCA pump, a membrane protein of about 110kDa, transports two Ca(2+) ions per ATP hydrolyzed from the cytoplasm to the lumen of the sarcoplasmic reticulum. In muscle cells, its ability to remove Ca(2+) from the cytosol induces relaxation. The transport mechanism employed by the enzyme from rabbit muscle has been extensively studied, and several crystal structures representing different conformational states are available. However, no structure of the pump from other sources is known. In this paper we describe the crystal structure of the bovine enzyme, crystallized in the E1 conformation and determined at 2.9Å resolution. The overall molecular model is very similar to that of the rabbit enzyme, as expected by the high amino acid sequence identity. Nevertheless, the bovine enzyme has reduced catalytic activity with respect to the rabbit enzyme. Subtle structural modifications, in particular in the region of the long loop that protrudes into the SR lumen connecting transmembrane α-helices M7 and M8, may explain the difference.
authors.affiliation: Department of Experimental Veterinary Sciences, Viale dell'Università 16, 35020 Legnaro, Padua, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Sacchetto
authors.forename: Ilenia
authors.initials: I
authors.lastname: Bertipaglia
authors.forename: Sara
authors.initials: S
authors.lastname: Giannetti
authors.forename: Laura
authors.initials: L
authors.lastname: Cendron
authors.forename: Francesco
authors.initials: F
authors.lastname: Mascarello
authors.forename: Ernesto
authors.initials: E
authors.lastname: Damiani
authors.forename: Ernesto
authors.initials: E
authors.lastname: Carafoli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zanotti
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D055162:Biocatalysis; D002417:Cattle; D003460:Crystallization; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D018482:Muscle, Skeletal / Q000201:enzymology*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000737:chemistry*
chemical_list: D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases