Protein secretion eukaryotic

Sakaguchi, M. (1997). Eukaryotic protein secretion. Cun. Opin. Biotechnol. 8, 595—601. 

Secreted proteins from eukaryotic cell lines present problems in purification due to both the volume of... 

Kelly, R, B. (1985). Pathways of protein secretion in eukaryotes. Scrence 230,25-31,... 

Recent work indicates that a major virulence mechanism for Salmonella may involve type III secretion systems, which are encoded on plasmids and allows direct transfer of bacterial proteins to eukaryotic cells through a contact-dependent secretion mechanism. These effector proteins are capable of enhancing virulence and epithelial cell invasion. 

The genetic evidence presented above makes it clear that E. coli, and possibly other bacteria, possess a complex set of proteins that act in the protein-secretion process. Although it appears that at least one protein, the M13 phage coat protein, can be localized and processed in the absence of proteins other than signal peptidase (Section V,B) (Silver et al., 1981 Ohno-Iwashita and Wickner, 1983 Watts et al., 1981), most proteins of the bacterial cell envelope require the participation of a secretion apparatus for proper localization. Whether the bacterial secretion process is analogous to the eukaryotic process remains to be seen. The recent development of in vitro translocation systems derived from E. coli should facilitate research in this area (Rhoads et al., 1984 Muller and Blobel, 1984b). 

The functions of about half the proteins in humans, roundworms, yeast, and several other eukaryotic organisms have been predicted based on analyses of genomic sequences (Chapter 9). Such analyses have revealed that at least 10-15 percent of the proteins in eukaryotes function as secreted ex-... 

The type III secretion apparatus, used by pathogenic bacteria to inject proteins into eukaryotic cells, consists of a basal portion that spans both membranes and an extracellular needlelike structure that can penetrate the plasma membrane of a target cell (see Figure 16-24). 

Folding and secretion of native protein from eukaryotic cell... 

Figure 1 Recombinant chemokine production reproduces the natively folded bioactive protein secreted from eukaryotic cells. (A) Folding, transport, and secretion of chemokines in eukaryotic cells. (B) Schematic diagram of expression, purification, and refolding of recombinant chemokines from coli. (C) The 3D structure of human CXCL12 illustrates the conserved chemokine fold with structurally important disulfide bonds and functionally important native N-terminus.

Nagamune, K., Beatty, W.L., and Sibley, L.D. (2007a) Artemisinin induces calcium-dependent protein secretion in the protozoan parasite Toxoplasma gondii. Eukaryot Cell 6 2147-2156. 

Vesicular proteins and lipids that are destined for the plasma membrane leave the TGN sorting station continuously. Incorporation into the plasma membrane is typically targeted to a particular membrane domain (dendrite, axon, presynaptic, postsynaptic membrane, etc.) but may or may not be triggered by extracellular stimuli. Exocytosis is the eukaryotic cellular process defined as the fusion of the vesicular membrane with the plasma membrane, leading to continuity between the intravesicular space and the extracellular space. Exocytosis carries out two main functions it provides membrane proteins and lipids from the vesicle membrane to the plasma membrane and releases the soluble contents of the lumen (proteins, peptides, etc.) to the extracellular milieu. Historically, exocytosis has been subdivided into constitutive and regulated (Fig. 9-6), where release of classical neurotransmitters at the synaptic terminal is a special case of regulated secretion [54]. 

All eukaryotic cells possess an unspecialized exocytic pathway known as the constitutive secretion. Vesicle membranes in this pathway fuse with the plasma membrane without any extracellular signal. As noted above, proteins destined for the secretory pathway are sorted at the level of the TGN. Proteins to be transported to the plasma membrane are directed into a constitutive secretory pathway. 

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