What are the major motor proteins in a cell?

The major motor proteins in a cell are indeed myosin, kinesin, and dynein, which play essential roles in cellular movement and transport. Myosin is primarily associated with muscle contraction and movement along actin filaments, allowing muscle cells to contract and enabling cell movement. Kinesin and dynein are crucial for intracellular transport; kinesin moves cargo toward the plus end of microtubules, while dynein carries it toward the minus end. These motor proteins work together to facilitate various cellular activities, including the movement of organelles, vesicles, and chromosomes during cell division.

Other options contain proteins that serve different functions. Actin, keratin, and collagen are structural proteins that provide support and shape to cells and tissues, but they are not classified as motor proteins. Troponin and tropomyosin, which regulate actin during muscle contraction, are associated with myosin, but they themselves do not serve as motor proteins. Lastly, globulin, albumin, and fibrinogen are types of blood proteins that primarily have roles in immunity, transport, and coagulation, not in cellular movement. Therefore, myosin, kinesin, and dynein are specifically recognized as the main motor proteins responsible for movement