The trans Golgi Network: Sorting at the Exit Site of the Golgi Complex

Abstract

The Golgi complex is a series of membrane compartments through which proteins destined for the plasma membrane, secretory vesicles, and lysosomes move sequentially. A model is proposed whereby these three different classes of proteins are sorted into different vesicles in the last Golgi compartment, the trans Golgi network. This compartment corresponds to a tubular reticulum on the trans side of the Golgi stack, previously called Golgi endoplasmic reticulum lysosomes (GERL).

Ultrastructural localization of enzymatic activity during spermiogenesis in two phytophagous bugs (Hemiptera: Pentatomidae)

“…Our observations show that acid phosphatase can be detected cytochemically in the Golgi complex, acrosome and axoneme. The acid phosphatase activity has been associated with the Golgi because, by definition, the trans Golgi network is the site where proteins finally exit from the Golgi to their respective cellular sites (Griffiths & Simons, 1986;Grab et al, 1997), i.e. plasma membranes, secretion granules and lysosomes.…”

Sorting and processing of secretory proteins

“…It is in the TGN [30] that proteins destined for the regulated pathway will be actively sorted from those to be released by the constitutive pathway (as discussed below in greater detail). The general features of the regulated pathway were described in a series of classic papers by Palade and co-workers in the late 1960s and early 1970s (reviewed by Palade himself in [31]).…”

“…The TGN, as the most distal compartment common to both the regulated and the constitutive pathways, is the sorting compartment As described above, all secretory proteins which initially present a signal sequence and are sequestered into the lumen of the RER are routed to the Golgi complex and, after intercisternal transport, arrive in the TGN [22,30] (Figure 1). This is one of the major protein sorting compartments of the cell, ensuring not only segregation of proteins destined for regulated or constitutive secretion, but also targeting of proteins to lysosomes and retention of Golgi proteins.…”

Sorting of growth hormone–erythropoietin fusion proteins in rat salivary glands

“…In the second pathway, the regulated secretory pathway (RSP), proteins destined for secretion are sorted and stored in high concentrations in secretory granules where they await an external secretory stimulus [3][4][5]. RSP proteins require an amino acid-based sorting signal and evidence supports both the "sortingfor-entry" and "sorting-by-retention" hypotheses for these proteins [6][7][8][9][10]. At present no universal sorting signals for secretory proteins have been identified in any cell type.…”