Search results
Results from the WOW.Com Content Network
The Golgi apparatus (/ ˈ ɡ ɒ l dʒ i /), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. [1] Part of the endomembrane system in the cytoplasm , it packages proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination.
The nucleolus (/ nj uː ˈ k l iː ə l ə s, ˌ nj uː k l i ˈ oʊ l ə s /; pl.: nucleoli /-l aɪ /) is the largest structure in the nucleus of eukaryotic cells. [1] It is best known as the site of ribosome biogenesis.
Diagram of the nucleus showing the ribosome-studded outer nuclear membrane, nuclear pores, DNA (complexed as chromatin), and the nucleolus. The nucleus contains nearly all of the cell's DNA , surrounded by a network of fibrous intermediate filaments called the nuclear matrix , and is enveloped in a double membrane called the nuclear envelope .
This is N-linked (O-linking occurs in the Golgi). N-linked glycosylation: If the protein is properly folded, oligosaccharyltransferase recognizes the AA sequence NXS or NXT (with the S/T residue phosphorylated) and adds a 14-sugar backbone (2-N-acetylglucosamine, 9-branching mannose, and 3-glucose at the end) to the side-chain nitrogen of Asn.
The cis-Golgi network is involved in the phosphorylation of oligosaccharides on lysosomal proteins, a modification that helps target proteins to the lysosomes. The medial-Golgi is the site of important reactions like the trimming of mannose and the addition of GlcNAc, which is essential for the formation of complex glycan structures.
Then the protein passes through the golgi apparatus, where it is packaged into a vesicle. In the vesicle, more parts are cut off, and it turns into mature insulin. In molecular biology, post-translational modification (PTM) is the covalent process of changing proteins following protein biosynthesis.
The proportion of cell volume that is cytosol varies: for example while this compartment forms the bulk of cell structure in bacteria, [9] in plant cells the main compartment is the large central vacuole. [10] The cytosol consists mostly of water, dissolved ions, small molecules, and large water-soluble molecules (such as proteins).
Christian de Duve, at the Laboratory of Physiological Chemistry at the Catholic University of Louvain in Belgium, had been studying the mechanism of action of insulin in liver cells. By 1949, he and his team had focused on the enzyme called glucose 6-phosphatase , which is the first crucial enzyme in sugar metabolism and the target of insulin.