Biomedical Engineering Reference
In-Depth Information
basolateral
3
1
4
apical
apical
2
3
FIGURE 13.2.
Intracellular trafficking of transport proteins in the hepatocyte. Newly syn-
thesized proteins are transported from the Golgi network in four possible directions. The first
pathway (1) represents direct trafficking of canalicular membrane proteins to the apical mem-
brane, where they are expressed immediately or (2) stored in subapical compartments until
some stimulus results in the mobilization of apical proteins to the membrane surface. Ba-
solateral proteins may be trafficked directly to the basolateral membrane (3) or stored in a
submembrane endosome until a signaling event causes them to be trafficked to the hepatocyte
surface. The insert represents the exocytic insertion and endocytic retrieval of the transport
proteins, depending on the intracellular status and signaling of the hepatocyte. The canalicular
proteins also may undergo indirect trafficking (4), where they are transported to the basolat-
eral membrane but never inserted into the plasma membrane, and then directed to the apical
membrane.
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