Membrane secretion

Transports into ER proteins destined for plasma membrane, secretion, or organelles Shuttles proteins between nucleus and cytoplasm Imports, by receptor-mediated endocytosis, lipid carrying particles... 

An important role in the nonspecific cellular response is played by Paneth cells which line the bottom of the intestinal glands. Their granules contain compounds that can damage bacteria. These include a lysozyme which damages peptidoglycan, the basic structure of Gram positive bacterial cellular membrane secreted phospholipase A2 involved in lipopolysaccharide metabolism and a-defensins, cryptydins, which decompose bacterial proteins. 

Since the PSV may be a tubular network rather than a series of distinct vesicles, secretion of the components may not require extensive vesicle fusion with the plasma membrane. Secretion parallels loss of UDP-Gal polysaccharide galactosyl transferase that is localized in the Golgi [189,190] suggesting that multiple secretory pathways may be coordinated to form the spore coat. 

Gerritse G, Ure R, Bizoullier F, Quax WJ (1998b) The phenotype enhancement method identifies the Xcp outer membrane secretion machinery from Pseudomonas alcaligenes as a bottleneck for lipase production. J Biotechnol... 

In subsequent studies attempting to find a correlation of physicochemical properties and antimicrobial activity, other parameters have been employed, such as Hammett O values, electronic distribution calculated by molecular orbital methods, spectral characteristics, and hydrophobicity constants. No new insight on the role of physiochemical properties of the sulfonamides has resulted. Acid dissociation appears to play a predominant role, since it affects aqueous solubiUty, partition coefficient and transport across membranes, protein binding, tubular secretion, and reabsorption in the kidneys. An exhaustive discussion of these studies has been provided (10). 

Three hormones regulate turnover of calcium in the body (22). 1,25-Dihydroxycholecalciferol is a steroid derivative made by the combined action of the skin, Hver, and kidneys, or furnished by dietary factors with vitamin D activity. The apparent action of this compound is to promote the transcription of genes for proteins that faciUtate transport of calcium and phosphate ions through the plasma membrane. Parathormone (PTH) is a polypeptide hormone secreted by the parathyroid gland, in response to a fall in extracellular Ca(Il). It acts on bones and kidneys in concert with 1,25-dihydroxycholecalciferol to stimulate resorption of bone and reabsorption of calcium from the glomerular filtrate. Calcitonin, the third hormone, is a polypeptide secreted by the thyroid gland in response to a rise in blood Ca(Il) concentration. Its production leads to an increase in bone deposition, increased loss of calcium and phosphate in the urine, and inhibition of the synthesis of 1,25-dihydroxycholecalciferol. 

One reason for this may be that the enzyme caimot be secreted, ie, transported across the cell membrane and cell wall of the host into the medium. 

Golgi apparatus A system of flattened membrane-bounded vesicles often stacked into a complex. Numerous small vesicles are found peripheral to the Golgi and contain secretory material packaged by the Golgi. Involved in the packaging and processing of macromolecules for secretion and for delivery to other cellular compartments. 

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