Coatomer
Encyclopedia
The coatomer is a protein
complex that coats membrane-bound transport vesicle
s. Three types of coatomers are known:
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
complex that coats membrane-bound transport vesicle
Vesicle (biology)
A vesicle is a bubble of liquid within another liquid, a supramolecular assembly made up of many different molecules. More technically, a vesicle is a small membrane-enclosed sack that can store or transport substances. Vesicles can form naturally because of the properties of lipid membranes , or...
s. Three types of coatomers are known:
- COPICOPICOPI is a protein complex that coats vesicles transporting proteins from the cis end of the Golgi complex back to the rough endoplasmic reticulum , where they were originally synthesized and between golgi compartments. This type of transport is termed as retrograde transport...
(retrograde transport from trans-Golgi apparatusGolgi apparatusThe Golgi apparatus is an organelle found in most eukaryotic cells. It was identified in 1898 by the Italian physician Camillo Golgi, after whom the Golgi apparatus is named....
to cis-Golgi and endoplasmic reticulumEndoplasmic reticulumThe endoplasmic reticulum is an organelle of cells in eukaryotic organisms that forms an interconnected network of tubules, vesicles, and cisternae...
) - COPIICOPIICOPII is a type of vesicle coat protein that transports proteins from the rough endoplasmic reticulum to the Golgi apparatus. This is termed anterograde transport. The name "COPII" refers to the specific coat protein complex that initiates the budding process...
(anterograde transport from ER to the cis-Golgi) - clathrinClathrinClathrin is a protein that plays a major role in the formation of coated vesicles. Clathrin was first isolated and named by Barbara Pearse in 1975. It forms a triskelion shape composed of three clathrin heavy chains and three light chains. When the triskelia interact they form a polyhedral lattice...
and its associated adaptinAdaptinAdaptins are proteins that mediate the formation of vesicles by clathrin-coated pits, through interaction with membrane-bound receptors. There are several types of adaptin, each related to a different group of such receptors....
s (endocytosisEndocytosisEndocytosis is a process by which cells absorb molecules by engulfing them. It is used by all cells of the body because most substances important to them are large polar molecules that cannot pass through the hydrophobic plasma or cell membrane...
from the plasma membrane, and trans-Golgi to lysosomes)