Electron microscopy of serum amyloid protein in the presence of calcium; alternative forms of assembly of pentagonal molecules in two-dimensional lattices

Publisher Website
Google Scholar
Abstract
The P component is a protein believed to be of serum origin commonly found in the highly ordered proteinaceous tissue deposits called amyloid. Both the protein recovered from the tissue and its serum counterpart have an identical characteristic EM appearance, consisting of pentagonal plates which are often assembled as columns of stacked discs. These images, seen in the absence of Ca, are replaced by 3 more complex assemblies when low concentrations of Ca are present. One of the structures is crystalline, the other 2 appear to be planar lattices, one having a distinguishable structure with 3-fold symmetry. The structural elements of the other lattice which takes the form of a cylinder are less distinct. The regular arrays which P component forms in the presence of Ca may be the basic framework on which amyloid deposits form.