Figure 2. The percent distribution of annotated functions for identified phosphoproteins in normal human lenses. After being identified by using gel-free IMAC phosphopeptide enrichment and LC-MS/MS analysis, phosphoproteins were classified into five functional categories annotated in the proteomic databank. The proportions of annotated functions related to protein folding, metabolism, and cytoskeleton were 32%, 28%, and 25%, respectively. The other 15% identified proteins belonged to protein families of transport, cellular redox homeostasis, and other unidentified functions.