Transport vesicles can move molecules between locations inside the cell, e.g., proteins from the rough endoplasmic reticulum to the Golgi apparatus. Membrane-bound and secreted proteins are made on ribosomes found in the rough endoplasmic reticulum. These proteins travel within the cell inside of transport vesicles.

Transport vesicles help move materials, such as proteins and other molecules, from one part of a cell to another. When a cell makes proteins, transporter vesicles help move these proteins to the Golgi apparatus for further sorting and refining.

Exocytosis (exo = external, cytosis = transport mechanism) is a form of bulk transport in which materials are transported from the inside to the outside of the cell in membrane-bound vesicles that fuse with the plasma membrane. Diagram illustrating the process of exocytosis.

endocytosis

In addition to SNAREs, vesicle fusion requires at least two other types of proteins. Following the formation of complexes between complementary SNAREs and membrane fusion, a complex of two additional proteins (the NSF/ SNAP complex) is needed to complete the process of vesicle transport.

Vesicle transport requires energy, so it is also a form of active transport. There are two types of vesicle transport: endocytosis and exocytosis.

Endocytosis methods require the direct use of ATP to fuel the transport of large particles such as macromolecules; parts of cells or whole cells can be engulfed by other cells in a process called phagocytosis.

There are two major ways that molecules can be moved across a membrane, and the distinction has to do with whether or not cell energy is used. Passive mechanisms like diffusion use no energy, while active transport requires energy to get done.