transcytoses

Transcytoses refer to the transport of substances, such as proteins and vesicles, across a cell membrane through a membranous vesicle that buds from one side of the cell and fuses with the other side. This process is distinct from endocytosis, where vesicles form on the surface of the cell and fuse with lysosomes, and from exocytosis, where vesicles fuse with the surface of the cell and release their contents.

In transcytosis, the vesicle buds from the transferrin receptor or other proteins engaged in selective receptor-mediated endocytosis. The vesicle then travels across the cell, often taking a circuitous route within the cell, before fusing with the opposite side of the cell, often with the same specificity as the protein that was first encountered. This can result in the transport of molecules between the same type of cells or from one type of cell to another.

Transcytosis is an essential process in maintaining cellular homeostasis. For example, it is necessary for the transport of iron across the blood-brain barrier in vertebrates. It plays a role in various physiological and pathological conditions, such as movement of amyloid proteins in Alzheimer's disease, keratin filaments in psoriasis, and immunoglobulin to lymphatic organs.

Transcytosis can be influenced by various mechanisms, such as receptor internalization rates, intracellular routing, exposition to different effectors and adaptors. Impaired function of transcytosis can be linked to various diseases, illustrating the importance of maintaining proper transport across a correct cell. Despite the role of transcytosis in cellular homeostasis, a complete understanding of the process is an ongoing area of research.