Final answer:
Myosin-I is present in various types of cells, mainly in muscle cells such as skeletal and cardiac muscles, and it aids in cell motion tasks, including cellular division and cytoplasmic streaming. It possesses ATPase activity and supports the sliding filament model of muscle contraction.
Step-by-step explanation:
Myosin-I is present in many types of cells, particularly those involved in muscle contraction, such as skeletal muscle cells and cardiac muscle cells. It also plays a role in cellular events requiring motion, including cell division in eukaryotic cells and cytoplasmic streaming in plant cells. Myosin-I interacts with actin, another contractile protein, and this interaction enables actin to perform functions related to motion and muscle contraction. Variations of myosin-I are encoded by a large eukaryotic gene family, indicating its widespread presence across various cell types.
In addition, myosin-I and related isoforms possess ATPase activity and contribute to cell motility. They can decorate actin, showing their functional importance across species. The evidence of myosin's role in contraction was demonstrated through experiments where actinomyosin preparations contracted when ATP was added, supporting the sliding filament model of muscle contraction.