COP I & II and Clathrin
COP I, COP II, and Clathrin are coat proteins responsible for directing vesicle movement inside the cell, especially to and from the Golgi Apparatus.
COP I coats vesicles transporting proteins from the cis-Golgi back to the rough endoplasmic reticulum (ER) and between Golgi compartments. This type of transport is termed as retrograde (backwards) transport.
COP II coats vesicles transporting proteins from the rough endoplasmic reticulum to the cis-Golgi. This process is termed anterograde (forwards) transport.
Clathrin is a coat protein with diverse functions. The most important functions are (1) endocytosis and vesicle trafficking to endosomes, which includes specialized endocytosis of fluids known as pinocytosis, as well as (2) vesicle transport to lysosomes.
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