The vesicular-tubular cluster (VTC), also referred to as the endoplasmic-reticulum–Golgi intermediate compartment (ERGIC), is an

organelle In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as organs are to the body, hence ''organelle,'' the ...

in eukaryotic cells. This compartment mediates trafficking between the

endoplasmic reticulum The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( ...

(ER) and

Golgi complex The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles insi ...

, facilitating the sorting of cargo. The cluster was first identified in 1988 using an antibody to the protein that has since been named

ERGIC-53 Protein ERGIC-53 also known as ER-Golgi intermediate compartment 53 kDa protein or lectin mannose-binding 1 is a protein that in humans is encoded by the ''LMAN1'' gene. Function ERGIC-53 (also named LMAN1) is a type I integral membrane protein ...

. In

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

ian organisms,

COPII The Coat Protein Complex II, or COPII, is a group of proteins that facilitate the formation of vesicles to transport proteins from the endoplasmic reticulum to the Golgi apparatus or endoplasmic-reticulum–Golgi intermediate compartment. This ...

vesicles that have budded from exit sites in the endoplasmic reticulum lose their coats and fuse to form the vesicular-tubular cluster (VTC). Retrieval (or retrograde) transport in

COPI COPI is a coatomer, a protein complex that coats vesicles transporting proteins from the ''cis'' end of the Golgi complex The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most ...

vesicles returns many of the lost ER resident proteins back to the endoplasmic reticulum. Forward (or anterograde) transport moves the VTC contents to the cis-Golgi network, the receiving face of the Golgi complex. This process is thought to occur by one of two processes. One is known as cisternal maturation where the VTC simply matures into the cis-Golgi network. In another,

vesicular transport moves VTC material to the receiving face of the Golgi apparatus through movement of the VTC along microtubules. Evidence exists for both processes and it may be that both occur simultaneously in cells.

References

{{reflist Organelles