Vacuolar

Vacuolar refers to anything pertaining to vacuoles, which are membrane-bound compartments found in many cell types. The term comes from the Latin vacuus, meaning empty. In cell biology, vacuolar elements include the organelles themselves and the processes associated with them.

In plants, fungi, and some protists, vacuoles can occupy a large portion of the cell’s interior. In animal cells they are typically smaller and more numerous. The surrounding membrane is called the tonoplast in plants and fungi; other organisms have different vacuolar membranes. The vacuole lumen often contains water, inorganic ions, metabolites, pigments, or toxic compounds, and its contents can vary by cell type and condition.

Functions of vacuoles are diverse. They help regulate osmotic balance and turgor pressure in plant cells, contributing to structural support. They serve as storage sites for nutrients, waste products, and secondary metabolites, and can sequester toxic compounds to protect the cytoplasm. Vacuoles also participate in digestion and recycling through hydrolytic enzymes, particularly in plant and fungal cells, where they function similarly to lysosomes in animal cells. Proton pumps and transporters, including vacuolar H+-ATPases, help maintain internal pH and drive the movement of ions and solutes.

Common vacuole types include the central vacuole of plant cells, smaller vacuoles in animal cells, food vacuoles in some protists, and contractile vacuoles in certain freshwater protists that expel excess water. During autophagy, vacuoles participate in the degradation and turnover of cellular components through specialized autophagic vacuoles. Vacuolar pathology sometimes refers to cellular changes where vacuoles accumulate abnormally.