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Protein targeting or protein sorting is the biological mechanism by which proteins are transported to their appropriate destinations within or outside the cell. 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. Information contained in the protein itself directs this delivery process. Correct sorting is crucial for the cell; errors or dysfunction in sorting have been linked to multiple diseases.
Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thylakoids frequently form stacks of disks referred to as grana. Grana are connected by intergranal or stromal thylakoids, which join granum stacks together as a single functional compartment.
Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical mechanism of cell secretion is via secretory portals at the plasma membrane called porosomes. Porosomes are permanent cup-shaped lipoprotein structures embedded in the cell membrane, where secretory vesicles transiently dock and fuse to release intra-vesicular contents from the cell.
In molecular biology, elastase is an enzyme from the class of proteases (peptidases) that break down proteins. In particular, it is a serine protease.
Pseudomonas aeruginosa is a common encapsulated, gram-negative, aerobic–facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, P. aeruginosa is a multidrug resistant pathogen recognized for its ubiquity, its intrinsically advanced antibiotic resistance mechanisms, and its association with serious illnesses – hospital-acquired infections such as ventilator-associated pneumonia and various sepsis syndromes.
Moraxella catarrhalis is a fastidious, nonmotile, Gram-negative, aerobic, oxidase-positive diplococcus that can cause infections of the respiratory system, middle ear, eye, central nervous system, and joints of humans. It causes the infection of the host cell by sticking to the host cell using trimeric autotransporter adhesins.
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The bacterial outer membrane is found in gram-negative bacteria. Its composition is distinct from that of the inner cytoplasmic cell membrane - among other things, the outer leaflet of the outer membrane of many gram-negative bacteria includes a complex lipopolysaccharide whose lipid portion acts as an endotoxin - and in some bacteria such as E. coli it is linked to the cell's peptidoglycan by Braun's lipoprotein.
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Translocase is a general term for a protein that assists in moving another molecule, usually across a cell membrane. These enzymes catalyze the movement of ions or molecules across membranes or their separation within membranes. The reaction is designated as a transfer from “side 1” to “side 2” because the designations “in” and “out”, which had previously been used, can be ambiguous. Translocases are the most common secretion system in Gram positive bacteria.
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References
- ↑ Sargent, F.; Berks, B.C.; Palmer, T. (2006). "Pathfinders and trailblazers: a prokaryotic targeting system for transport of folded proteins". FEMS Microbiol. Lett. 254 (2): 198–207. doi: 10.1111/j.1574-6968.2005.00049.x . PMID 16445746.
- ↑ Carrie, Chris; Weißenberger, Stefan; Soll, Jürgen (2016-10-15). "Plant mitochondria contain the protein translocase subunits TatB and TatC". Journal of Cell Science. 129 (20): 3935–3947. doi: 10.1242/jcs.190975 . ISSN 0021-9533. PMID 27609835.
- ↑ Bennewitz, Bationa; Sharma, Mayank; Tannert, Franzisca; Klösgen, Ralf Bernd (November 2020). "Dual targeting of TatA points to a chloroplast-like Tat pathway in plant mitochondria". Biochimica et Biophysica Acta (BBA) - Molecular Cell Research. 1867 (11): 118816. doi: 10.1016/j.bbamcr.2020.118816 . PMID 32768405. S2CID 224889980.
- ↑ Barnett JP, Eijlander RT, Kuipers OP, Robinson C (2008). "A minimal Tat system from a gram-positive organism: a bifunctional TatA subunit participates in discrete TatAC and TatA complexes". J. Biol. Chem. 283 (5): 2534–2542. doi: 10.1074/jbc.M708134200 . PMID 18029357.
- ↑ Chaddock, A.M.; Mant, A.; Karnauchov, I.; Brink, S.; Herrmann, R.G.; Klösgen, R.B.; Robinson, C. (1995). "A new type of signal peptide: central role of a twin-arginine motif in transfer signals for the delta pH-dependent thylakoidal protein translocase". EMBO J. 14 (12): 2715–2722. doi:10.1002/j.1460-2075.1995.tb07272.x. PMC 398390 . PMID 7796800.
- ↑ Frielingsdorf, S.; Klösgen, R.B. (2007). "Prerequisites for Terminal Processing of Thylakoidal Tat Substrates". J. Biol. Chem. 282 (33): 24455–24462. doi: 10.1074/jbc.M702630200 . PMID 17581816.
- ↑ Sargent F, Bogsch EG, Stanley NR, Wexler M, Robinson C, Berks BC, Palmer T (1998). "Overlapping functions of components of a bacterial Sec-independent protein export pathway". EMBO Journal. 17 (13): 3640–50. doi:10.1093/emboj/17.13.3640. PMC 1170700 . PMID 9649434.
- ↑ Gouffi K, Santini CL, Wu LF (August 2002). "Topology determination and functional analysis of the Escherichia coli TatC protein". FEBS Lett. 525 (1–3): 65–70. doi:10.1016/s0014-5793(02)03069-7. PMID 12163163.
- ↑ Organism