Secretion granules

Catecholamines Are Synthesized In Final Form Stored In Secretion Granules... 

DBH is a monooxygenase and uses ascorbate as an electron donor, copper at the active site, and fiimarate as modulator. DBfl is in the particulate fraction of the medullary cells, probably in the secretion granule thus. 

SG, secretion granule V, vacuole Nu, nucleolus G, Golgi apparatus CW, cell wall (of a plant)... 

These secretion granules move to the surface and are released from the cell. In this process of exocytosis the membranes surrounding the granules fuse with the outer cell membrane. The rough ER appears to contribute membrane material to the smooth ER and Golgi apparatus, while material from Golgi membranes can become incorporated into the outer cell membrane and into lysosomes. Outer mitochondrial membranes and membranes around vacuoles in plant cells may also be derived directly from the ER. Outer membrane materials are probably "recycled" by endocytosis. 

Dog platelets readily secrete granule contents in le nse to agonists including ADP, collagen, thrombin, and PAF (Boudreaux et al. 1994 Thomas 1996). 

While there are still questions to be answered regarding the mechanisms of CTL-mediated cytotoxicity at mucosal surfeces, the current consensus is that multiple mechanisms, including perforin secretion, granule enzyme secretion and initiation of apoptosis, may account for CTL-mediated cytotoxicity (Smyth et al., 1992). 

Despommier DD, Miiller M (1976) The stichosome and its secretion granules in the mature muscle larva of Trichinella spiralis. J Parasitol 62 775-785 Despommier DD, Gold AM, Buck SW, Capo V, SUberstein D (1990) Trichinella spiralis secreted antigen of the infective LI larva locaUzes to the cytoplasm and nucleoplasm of infected host cells. Exp Parasitol 71 27-38... 

Cameron, R., et al. (1986). A Common Spectrum of Polypeptides Occurs in Secretion Granule Membranes of Different Exocrine Glands, J Cell Biol. 103 1299-1313. 

Many, if not most, of the proteins secreted by cells are glycoproteins and recent evidence suggests that the Golgi apparatus (see below) may be responsible for adding the carbohydrate moiety to the newly synthesized polypeptide chains. It may also be responsible for packaging the secretory proteins into membrane-bound vesicles or secretion granules. 

The Golgi apparatus consists of a stack of membrane sacs and associated vesicles. It is an extension of the ER. Transfer vesicles transport the proteins issued from the ER to the sacs of the Golgi apparatus. The Golgi apparatus has a dual function. It is responsible for the glycosylation of protein, then sorts so as to direct them via specialized vesicles either into the vacuole or into the plasmic membrane. An N-terminal peptidic sequence determines the directing of proteins towards the vacuole. This sequence is present in the precursors of two vacuolar-orientated enzymes in the yeast Y carboxypeptidase and A proteinase. The vesicles that transport the proteins of the plasmic membrane or the secretion granules, such as those that transport the periplasmic invertase, are still the default destinations. 

Amatore, C., Arbault, S., Bonifas, 1. et al. 2007. Relationship between amperometric pre-spike feet and secretion granule composition in Chromaffin cells An overview. Biophys. Chem. 129 181-189. 

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