Tomographic image analysis of cryo-ET data was carried out with the Inspect3D Xpress software package (FEI Company, Hillsboro, Oregon, USA). The tomographic images were aligned to each other by a two-step process. The first step involved alignment of adjacent images by cross correlation. This process was repeated several times until the shift between adjacent images was below one pixel in either the X or Y plane. The second step involved the alignment of the entire image stack using 10 nm colloidal gold particles as fiducial markers. In this instance the term ''image stack'' refers to all the images collected in a single tomographic tilt. This procedure involves the selection of ten to twenty of the 10 nm gold particles and the subsequent identification and tracking of these particles in all of the images in the image stack. The locations of these particles are then used in conjecture with the tilt angles of each image to globally align all of the images to each other. The last step in this process was to calculate the three dimensional reconstruction of the tomogram from the aligned images. In this study we used the simultaneous iterative reconstruction technique (SIRT) algorithm with 10 iterations to calculate the final three-dimensional reconstruction (tomogram).