BaSIC STRuCTuRE aNd fuNCTION Of CEllS
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salts. Traffic between the endoplasmic reticulum and the Golgi appara- Endocytic (internalization) pathway
tus is bidirectional and takes place via carrier vesicles derived from the
The endocytic pathway begins at the plasma membrane and ends in
donor site that bud, tether and fuse with the target site.
lysosomes involved in the degradation of the endocytic cargo through
Golgins are long coiled-coil proteins attached to the cytoplasmic
the enzymatic activity of lysosomal hydrolases. Endocytic cargo is
surface of cisternal membranes, forming a fibrillar matrix surrounding
internalized from the plasma membrane to early endosomes and
the Golgi apparatus to stabilize it; they have a role in vesicle trafficking
then to late endosomes. Late endosomes transport their cargo to lyso-
(for further reading on golgins, see Munro 2011). The Golgi apparatus
somes, where the cargo material is degraded following fusion and
has several functions: it links anterograde and retrograde protein and