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. Author manuscript; available in PMC: 2008 Dec 1.
Published in final edited form as: Exp Eye Res. 2007 Aug 24;85(6):749–761. doi: 10.1016/j.exer.2007.08.009

Figure 7. Cellular model for the PRL traffic in lacrimal acinar cells.

Figure 7

The major traffic apparatus diverge from, and reconverge with, the biosynthetic apparatus, i.e., the endoplasmic reticulum (ER) and Golgi complex, at the trans-Golgi network (TGN), the cell’s major sorting nexus. The constitutive transcytotic - paracrine apparatus consists of the recycling endosome (recyc.end.) and early endosome (early end.). The apparatus for regulated exocrine secretion of proteins consists of the immature secretory vesicle (isv) and mature secretory vesicles (esv). The apparatus for autophagy and degradation of proteins, lipids, and carbohydrates consists of the autophagosome (aps), pre-lysosome (prelys.), and autolysosome (alys), as well as the late endosome (late end.) and storage lysosome (slys.). Whether endocytosed from the ambient medium or emerging from the biosynthetic apparatus, PRL traffics through the TGN to the immature secretory vesicles as well as to the endosomes. Elevated levels of PRL suppress expression of the regulated exocrine apparatus and induce expression of the regulated paracrine apparatus, which consists of the immature secretory vesicle and paracrine secretory vesicles (ppsv). In reducing the cell’s content of rab7, elevated PRL also suppresses traffic into the autophagic - lysosomal apparatus.