부산대학교 도서관

Several structures of the Ryanodine receptor in different functional states with various bound ligands have been determined using electron cryo-microscopy in recent years. These structures have varied in resolution from 25-40Å, however, to date, none have been corrected for the CTF (contrast transfer function) of the microscope. The CTF can have a significant effect on the detailed structure of the molecule, causing features in the 40-70Å range to be unnaturally emphasized. This causes small holes to become larger and small protrusions to become elongated. Unfortunately due to zero points in the CTF, correction cannot be properly accomplished with individual images. Several approaches to correcting the CTF have been proposed and/or used by combining information from images taken at different defocus settings. We have taken the approach of performing CTF correction as a preprocessing step. There are both advantages and disadvantages to this method. There are 2 primary advantages: First, by combining data from identical regions of focal pairs,