H. Ogawa et al., STRUCTURE OF THE CA2-RETICULUM - A VIEW ALONG THE LIPID BILAYER AT 9-ANGSTROM RESOLUTION( PUMP OF SARCOPLASMIC), Biophysical journal, 75(1), 1998, pp. 41-52
We have used multilamellar crystals of the ATP-driven calcium pump fro
m sarcoplasmic reticulum to address the structural effects of calcium
binding to the enzyme. They are stacks of disk-shaped two-dimensional
crystals. A density map projected along the lipid bilayer was obtained
at 9-Angstrom resolution by frozen-hydrated electron microscopy. Alth
ough only in projection, much more details of the structure were revea
led than previously available, especially in the transmembrane region.
Quantitative comparison was made with the model obtained from the tub
ular crystals of this enzyme formed in the absence of calcium. Unexpec
tedly large differences in conformation were found, particularly in th
e cytoplasmic domain.