Final answer:
Myosin-I is a motor protein found in eukaryotic cells, particularly muscle cells and those that change shape, and is involved in cell motility and muscle contraction.
Step-by-step explanation:
Myosin-I is present in various types of eukaryotic cells, where it plays a critical role in cell motility and muscle contraction. This motor protein interacts with actin microfilaments to facilitate movement within cells, including processes such as cell division and cytoplasmic streaming, particularly in muscle cells and cells that change shape like phagocytes. All isoforms of myosin, including myosin-I, have ATPase activity and are capable of decorating actin filaments, confirming their involvement in cellular motion.