The Secretory Pathway in Eukaryotic Cells

The endoplasmic reticulum is specialised for protein processing and lipid biosynthesis. One of its primary functions is to regulate the ionic concentration in the cytoplasm via the movement of Ca2+, via ionic pumps and channels. It also contains enzymes responsible for the metabolising of drugs. Endoplasmic reticulum (ER) can come in two forms. As depicted in Fig. 2 Rough ER has ribosomes present as part of the membrane of the organelle, and together with these ribosomes takes polypeptides and amino acids from the cytosol and synthesises proteins destined for attachment to cell membranes. It is in the lumen of the rough ER that the proteins are folded into the specific three dimensional shapes that are so important for biochemical recognition and linking sites [6]. It is called rough because of the presence of ribosomes makes the surface of the membrane look rough, unlike smooth ER, which lacks the ribosomes so the membrane looks smooth. Rough ER is composed of a large but convoluted flattened sac. The main function of the smooth ER is the production of lipids and the metabolism of compounds (such as the breakdown of glycogen into glucose). Because of the different functions between the rough and smooth ER, different specialised cells will have different amounts of each; for example, hepatic

One of the main manufacturing facilities within a cell. Consists of rough ER and smooth ER, they are physically connected but differ in structure. Consist of membrane-enclosed tubes and sacs within the cytoplasm. Rough ER, named for the ribosomes attached to its surface, make membrane and secretory proteins. One function of rough ER is to produce new membrane. Some products by rough ER are dispatched to other locations by transport vesicles.

There are two types of Endoplasmic Reticulum the Smooth ER and the Rough ER. you can distinguish that both of the ER’s are different to each other, this is shown in the diagram above that one is smooth ER and the other is rough ER the rough ER has ribsomes attracted to it while the smooth ER does not have ribosomes attached to it. The two ER’s have different function to each other.

The body has two faces, the cis face which fuses with incoming transport vesicles, and the trans face which excretes the secretory vesicles. The cis face fuses with vesicles coming from the ER effectively from many directions due to its convex shape, whereas the concave trans face can direct the secretory vesicles to their destination. When fusing with the cis face, the transport vesicles release their proteins to be absorbed for modification. Each cisternal layer of the Golgi body holds different enzymes which each modify the passing proteins in separate ways. Between the layers the proteins are moved through the gaps by small vesicles. When a protein has been modified correctly, it leaves the Golgi body via secretory vesicles which then carry the modified proteins to the cell membrane or another organelle. The proteins that are transported to the cell membrane are either excreted from the cell, or absorbed into the membrane to aid with its function. Some of the secretory vesicles which hold hydrolytic enzymes stay within the cytoplasm and function as lysosomes.

The function of the Golgi apparatus is to modify, sort, and package proteins and other materials from the endoplasmic reticulum for storage in the cell or secretion outside the cell.

The golgi complex is a structure composed of flattened sacs known as cisternae. It is involved in the modification and packaging of proteins, the manufacturing of lysosomes and transport of products via vesicles. (Bailey, R, 2013)

This is a series of flattened, fluid-filled sacs stacked like pancakes. The Golgi apparatus is believed to package proteins for delivery to other organelles; it is also responsible for producing lysosomes.

The ER makes lipids, breaks down and packages proteins for the Golgi complex. The Golgi Complex processes and transports and proteins out the cell. (Nnpdf.org, 2016)

SMS and cells also both have a “golgi apparatus.” The function of the golgi apparatus is to modify, package, and sort proteins. This is similar to the job of the secretary. The secretary sorts and packages mail for the

Golgi Body: The golgi body packages, sorts things and sends things out of the cell. Like the red stitches on the leather casing sends things out side of the cell from the inside.

Proteins begin processing in the endoplasmic reticulum and continue being processed through ribosomes and the golgi apparatus.

Secretory Vesicles: the secretory vesicles moves the cell secretions that was inside of the golgi, to the cell surface and let it go

The plasma membrane is the outermost layer of a eukaryotic cell. It is made up of phospholipids and proteins. The plasma membrane also functions as the selective boundary of the cell. Unlike a prokaryotic cell, a eukaryotic cell has a nucleus. The nucleus is responsible for the storage and the protection of the DNA of the cell. Most eukaryotes possess a endomembrane system. The endomembrane consists of a endoplasmic reticulum, the golgi apparatus, and vesicles. The endomembrane makes lipids and membrane proteins and sends them where they need to go in the cell. Mitochondria are important parts of eukaryotic cells because they transfer the energy needed for the ATP from food molecules. Lastly, one of the major components of a eukaryotic cell is the cytoskeleton. The cytoskeleton is made up of actin microfilaments, microtubules, and intermediate filaments. The cytoskeleton gives the structure of the eukaryotic cell support. It also assists with the division of the cell and it controls cellular

The endoplasmic reticulum (ER) is an essential organelle that is a major place for the biogenesis of cellular components including proteins, lipids, and carbohydrates and internal calcium storage. ER is primarily responsible for protein translocation, protein folding and protein post modification. Proper folding of protein in the ER is accomplished with the aid of ER resident proteins or enzymes such as chaperones. Binding of chaperones to

Overexpression of the HEPN domain in HeLa cells following three hours of starvation indicates that sacsin plays a key role in lysosomal transport due to the reduced efficiency of perinuclear lysosomal clustering. HEPN’s property of dimerizing may be disrupting the function of with full-length sacsin by preventing endogenous sacsin from dimerizing within the cell. Thus, dimerization may be essential to sacsin’s function, particularly for binding JIP3, which is necessary for lysosomal transport7. HATPase 3 overexpression may be occupying JIP3 binding, but was not found to disrupt lysosomal localization following starvation, perhaps due to the truncated size of this deletion construct.