N-terminal signal peptide

The protein contains an N-terminal signal peptide of 17 amino acid residues for secretion. The luminescence reaction of coelenterazine catalyzed by the recombinant luciferase shows a luminescence emission maximum at 485 nm, whereas the luminescence catalyzed by the native luciferase shows a maximum at 480 nm. 

In a pioneering attempt, Sjostrom et al. (1987) performed a multivariate data analysis on the N-terminal signal peptides of E. coli proteins. 

The inner envelope membrane proteins have a cleavable N-terminal transit peptide, as well as some hydrophobic domain (s) in their mature portion. There are two possibilities on the role of this hydrophobic domain it may work as an N-terminal signal peptide after the translocation into the stroma and the subsequent cleavage of the transit peptide. Alternatively, it may work as a stop-transfer signal. One more important question is how the distinction is made between the outer membrane proteins, the inner membrane proteins, and the thylakoid membrane proteins. It is still an enigma. 

The mechanisms of ER protein sorting are relatively well known (Teas-dale and Jackson, 1996). Most, if not all, soluble ER proteins have a well-conserved C-terminal tetrapeptide, KDEL ( HDEL for yeasts) in addition to a cleavable N-terminal signal peptide. A small set of membrane proteins also has this signal at the C terminus. This signal... 

Proteins that are destined to be secreted or to end up as transmembrane proteins are synthesized with an N-terminal signal peptide. Signal peptides are highly hydrophobic sequences of variable length. Proteins synthesized with signal peptides are termed preproteins. For example, insulin is a secreted protein. It is therefore synthesized as a preprotein. It is also synthesized in inactive form a proprotein. Insulin as initially synthesized is, in consequence, a preproprotein. 

Preproprotein a proprotein synthesized with the N-terminal signal peptide targeting it... 

They may enter the cytosol and fold quickly into a compact form. This may require only a few seconds, whereas the translation process in the ribosome may take many seconds. The folding will therefore be cotranslational.525 Depending upon the N-terminal signal peptide the protein may later unfold and pass through a membrane pore or translocon into the endoplasmic reticulum (ER), a mitochondrion, chloro-plast, or peroxisome. Wherever it is, it will be crowded together with thousands of other proteins. It will interact with many of these, and evolution will have enabled some of these to become chaperones (discussed in Chapter 10).526... 

Proteins with N-terminal signal peptides or C-terminal membrane anchor regions and proteins where the N terminus contributes to the biological properties of the protein require special attention to achieve a satisfactory fusion A number of variants may need to be made and assayed. A protease-sensitive site may be designed into the amino acid sequence at the fusion point for eventual separation of the desired gene product from the fusion. 

Neuropeptide Y and its presynaptic receptors were discovered 25 years ago (Figure 1). There are four subtypes of neuropeptideY receptors, Yi, Y2, Y4 and Y5 (Table 1, Alexander et al. 2006) a fifth subtype, Y6, is functional in the mouse, whereas in primates the related gene is nonfunctional due to a frame-shift mutation (Alexander et al. 2006). Neuropeptide Y receptors are also activated by another two peptides, peptide YY (PYY) and pancreatic polypeptide (PP). The three peptides are not synthetized as such but are processed from larger precursors via two steps, i.e., an initial cleavage of the N-terminal signal peptide and the subsequent cleavage of the C-terminal part (Tatemoto 2004). The affinity of PYY is very similar to that... 

Secretory proteins have an N-terminal signal peptide which targets the protein to be synthesized on the rough endoplasmic reticulum (RER). During synthesis it is translocated through the RER membrane into the lumen. Vesicles then bud off from the RER and carry the protein to the Golgi complex, where it becomes glycosylated. Other vesicles then carry it to the plasma membrane. Fusion of these transport vesicles with the plasma membrane then releases the protein to the cell exterior. 

Proteins destined for the ER have an N-terminal signal peptide, are synthesized on the RER, are translocated into the RER lumen and transported by vesicles to the Golgi. Once there, a C-terminal amino acid sequence (KDEL) is recognized by a Golgi receptor protein that causes other vesicles to return the protein to the ER. 

The mRNA for the secretory protein binds to a free cytoplasmic ribosome and protein synthesis begins. The first part of the protein made is the N-terminal signal peptide. A signal recognition particle (SRP), which is a complex of a 7S RNA and six proteins, binds to the signal peptide and stops further protein synthesis. This stops the secretory protein from being released prematurely into the cytosol. The ribosome-mRNA-SRP complex now binds to an SRP receptor, a protein on the surface of the ER. The ER membrane also contains a ribosome receptor protein associated with a protein translocator. In a concerted series of reactions, the ribosome is held tightly by the ribosome receptor protein, the SRP... 

The large precursor of aqualysin I comprises four structurally distinguishable domains an N-terminal signal peptide (14 amino acid residues), an N-terminal pro-sequence (113... 

Fig. 1. Model for membrane protein insertion into the ER membrane. In stage I, an N-terminal signal peptide (not shown) has already initiated translocation across the membrane.

All type 1 copper proteins, with the exception of plastocyanin, possess an 20-amino acid N-terminal signal peptide (Figure 1). These peptides help the proteins translocate... 

A cDNA encoding human IL-17 (hIL-17) has been cloned from a CD4 T-cell library. The predicted 155-amino acid sequence contains an N-terminal signal peptide and exhibits 72% amino acid identity with HVS13 and 63% with murine CTLA-8, High levels of hIL-17 were induced from primary peripheral blood CD4 T cells on stimulation. When expressed in CVl/EBNA cells, recombinant hIL-17 was secreted in both glycosylated and nonglycosylated forms. An hIL-17 Fc fusion protein and supernatants from cells transfected with hIL-17 induced IL-6 and IL-8 production and enhanced the surface expression of the ICAM-1 in human fibroblasts. ... 

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