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After translation, proteins within the ER make sure that the protein is folded correctly. If after a first attempt the folding is unsuccessful, a second folding is attempted. If this fails too the protein is exported to the cytosol and labelled for destruction. Aside from the folding, there is also a sugar chain added to the protein.
Protein targeting or protein sorting is the biological mechanism by which proteins are transported to their appropriate destinations within or outside the cell. [ 1 ] [ 2 ] [ note 1 ] Proteins can be targeted to the inner space of an organelle , different intracellular membranes , the plasma membrane , or to the exterior of the cell via secretion .
A nuclear localization signal (NLS) is a target peptide that directs proteins to the nucleus and is often a unit consisting of five basic, positively charged amino acids. The NLS normally is located anywhere on the peptide chain. A nuclear export signal (NES) is a target peptide that directs proteins from the nucleus back to the cytosol. It ...
For movement between different compartments within the cell, vesicles rely on the motor proteins myosin, kinesin (primarily anterograde transport) and dynein (primarily retrograde transport). One end of the motor proteins attaches to the vesicle while the other end attaches to either microtubulees or microfilaments. The motor proteins then move ...
Secretion in bacterial species means the transport or translocation of effector molecules. For example: proteins, enzymes or toxins (such as cholera toxin in pathogenic bacteria e.g. Vibrio cholerae) from across the interior (cytoplasm or cytosol) of a bacterial cell to its exterior. Secretion is a very important mechanism in bacterial ...
The general secretion (Sec) involves secretion of unfolded proteins that first remain inside the cells. In Gram-negative bacteria, the secreted protein is sent to either the inner membrane or the periplasm. But in Gram-positive bacteria, the protein can stay in the cell or is mostly transported out of the bacteria using other secretion systems.
The translocon (also known as a translocator or translocation channel) is a complex of proteins associated with the translocation of polypeptides across membranes. [1] In eukaryotes the term translocon most commonly refers to the complex that transports nascent polypeptides with a targeting signal sequence into the interior (cisternal or lumenal) space of the endoplasmic reticulum (ER) from ...
The bacterial SecYEG channel interacts with the signal sequences of secretory proteins as well as SecA, an ATPase which drives translocation. SecY is an integral plasma membrane membrane protein of 419 to 492 amino acid residues that typically contains 10 transmembrane (TM), 6 cytoplasmic and 5 periplasmic regions. [4] Eukaryotic translocon ...