Final answer:
There are multiple actin binding protein families in eukaryotes. Actin is encoded by a large actin gene family with multiple isoforms involved in cytoskeletal function. Myosin genes also form a large gene family and encode isoforms with ATPase activity.
Step-by-step explanation:
There are multiple actin binding protein families in eukaryotes. Actin is encoded by a large actin gene family with at least six different isoforms. These isoforms have nearly identical amino acid sequences and are involved in cytoskeletal function. The most predominant isoform is ß-actin. Myosin genes also form a large eukaryotic gene family and encode variant isoforms with ATPase activity. Some isoforms are involved in cell motility. Overall, there are multiple actin binding protein families in eukaryotes that play important roles in cell structure and function.