As the saying goes, “arising tide lifts all boats.” The actin cytoskeleton is the cell’s rising tide, providing the rigidity that gives shape to cells and the tracks along which molecular motors pull organelles and vesicles through the cytoplasm. In recent years, cell biologists have discovered another way in which the actin cytoskeleton drives the cell’s motion: by assembling into actin filaments that are pushed along by pocket-sized water molecules.
Actin filaments are long, thin rods made of the protein actin. In many cell types, actin filaments are arranged in a dense network just below the cell membrane, where they provide strength and structure. But actin filaments are not just static scaffolding—they are dynamic and constantly in motion.
Cell biologists have known for some time that actin filaments are dynamic structures. They grow and shrink in a process called polymerization, and they are constantly being moved around by molecular motors. However, the role of water molecules in actin filament movement was not fully understood until recently.
In 2018, a team of researchers from Japan and the United States discovered that water molecules play an important role in actin filament movement. The team used cryo-electron microscopy to image actin filaments in the presence and absence of water.
They found that water molecules bind to the actin filaments and form a “cage” around them. This cage is made up of water molecules that are positioned just right to interact with the actin filaments. The water molecules bind to the actin filaments and push them along.
The researchers also found that the water molecules are not static—they are constantly moving and rotating. This means that the actin filaments are also constantly moving and rotating.
The discovery of the role of water molecules in actin filament movement has important implications for our understanding of cell motility. Water molecules are much smaller than actin filaments, and they are much more abundant in cells. This means that water molecules could be the cellular equivalent of a “muscle”, providing the force that moves cells.
The discovery of the role of water molecules in actin filament movement also has important implications for our understanding of diseases that involve the actin cytoskeleton. Many diseases, including cancer, are associated with changes in the actin cytoskeleton. The discovery of the role of water molecules in actin filament movement could help us to understand how these changes lead to disease.
A cell is a smallest structural and functional unit of an organism. It is the basic structural, functional, and biological unit of all known organisms. A typical prokaryotic cell is between 1 to 10 μm in diameter and is composed of a plasma membrane, cytoplasm, and a nucleoid. Eukaryotic cells are generally larger and more complex than prokaryotic cells, being typically 10–100 μm in diameter. They have a plasma membrane, cytoplasm, and a distinct nucleus containing most of the cell’s genetic material.
All cells arise from other cells through the process of cell division. In multicellular organisms, cells eventually die, either through programmed cell death or apoptosis.
In higher plants and animals, cells differentiate to form the various tissues and organs of the body.
The water molecules in a cell are constantly moving and changing position. The actin filaments in the cell are responsible for the cell’s motion. When the cell moves, the actin filaments slide past each other and change the shape of the cell. The actin filaments are also responsible for the cell’s ability to change shape and divide.