One of the most important processes required for the sustenance of cells is a function called endocytosis. Among other functions, endocytosis allows cells to engulf proteins and food or fluid matter from its surroundings. Endocytosis can occur through several pathways - the most well-characterized of these is mediated through a 'coat protein' (clathrin) and others, that do not require clathrin are collectively termed clathrin-independent processes. The clathrin-dependent endocytic pathway requires this 'coat protein' to induce the formation of 'buds' on the plasma membrane of cells which eventually 'pinch off' into vesicles. Clathrin-independent pathways, on the other hand, do not use clathrin in forming pits or buds prior to endocytosis and use other accessory proteins.