Nucleotide- and Protein-Dependent Functions of .

Cytoplasmic β- and γ-actin proteins are 99% identical but support unique organismal functions. The cytoplasmic actin nucleotide sequences  and , respectively, are more divergent but still 89% similar.  mice are embryonic lethal and  cells fail to proliferate, but editing the  gene to express γ-actin () resulted in none of the overt phenotypes of the knockout revealing protein-independent functions for .