Fig. 17.

Diagram showing the number of X-ray structures of proteins (soluble and membrane proteins) and solely membrane proteins deposited in the PDB since 1972 (annotation of the abscissa begins at 1974) (as of November 2014). Red diamonds represent the number of protein structures, whereas blue triangles indicate the number of crystallized membrane proteins. Only protein containing structures which have been solved by X-ray diffraction analysis (according to their UniProt number) where taken into account, so that every protein was included only once in the statistic.