Many proteins undergo modifications posttranslationally, meaning after a protein is synthesized. One example is arginylation, which is used to modify many proteins, including actin. A recent paper has looked at the effects of arginylation on the actin cytoskeleton, and found that arginylation is important for actin filament polymerization, actin network structure, and interaction with proteins that regulate actin. Image above shows the leading edges of crawling cells—wild-type (top) compared to arginylation-defective (bottom).
Reference: Sougata Saha, Maureen M. Mundia, Fangliang Zhang, Ryan W. Demers, Farida Korobova, Tatyana Svitkina, Alex A. Perieteanu, John F. Dawson, and Anna Kashina. Authors’ Molecular Biology of the Cell paper can be found here.