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(architecture) a statue or a human bust or an animal carved out of the top of a square pillar; originally used as a boundary marker in ancient Rome (同)terminal figure, term
either end of a railroad or bus route
the 14th letter of the Roman alphabet (同)n

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目的,終結 / (鉄道・バスの)終点,終着駅
nitrogenの化学記号
neodymiumの化学記号

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/10/26 23:46:33」(JST)

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A tetrapeptide (example: Val-Gly-Ser-Ala) with green highlighted N-terminal α-amino acid (example: L-valine) and blue marked C-terminal α-amino acid (example: L-alanine). This tetrapeptide could be encoded by the mRNA sequence 5'-GUUGGUAGUGCU-3'.

The N-terminus (also known as the amino-terminus, NH₂-terminus, N-terminal end or amine-terminus) refers to the start of a protein or polypeptide terminated by an amino acid with a free amine group (-NH₂). By convention, peptide sequences are written N-terminus to C-terminus, left to right in LTR languages. This correlates the translation direction to the text direction (because when a protein is translated from messenger RNA, it is created from N-terminus to C-terminus - amino acids are added to the carbonyl end).

Chemistry

Each amino acid has a carboxylic group and an amine group, and amino acids link to one another to form a chain by a dehydration reaction by joining the carboxyl group of one amino acid to the amine group of the next. Thus, polypeptide chains have an end with an unbound carboxyl group, the C-terminus, and a beginning with an amine group, the N-terminus.

When a protein is translated from messenger RNA, it is created from N-terminus to C-terminus. The amino end of an amino acid (on a charged tRNA) during the elongation stage of translation, attaches to the carboxyl end of the growing chain. Since the start codon of the genetic code codes for the amino acid methionine, most protein sequences start with a methionine (or, in bacteria, mitochondria and chloroplasts, the modified version N-formylmethionine, fMet). However, some proteins are modified posttranslationally, for example by cleavage from a protein precursor, and therefore may have different amino acids at their N-terminus.

Function

N-Terminal targeting signals

The N-terminus is the first part of the protein that exits the ribosome during protein biosynthesis. It often contains signal peptide sequences, "intracellular postal codes" that direct delivery of the protein to the proper organelle. The signal peptide is typically removed at the destination by a signal peptidase. The N-terminal amino acid of a protein is an important determinant of its half-life (likelihood of being degraded). This is called the N-end rule.

Signal peptide

The N-terminal signal peptide is recognized by the signal recognition particle (SRP) and results in the targeting of the protein to the secretory pathway. In eukaryotic cells, these proteins are synthesized at the rough endoplasmic reticulum. In prokaryotic cells, the proteins are exported across the cell membrane. In chloroplasts, signal peptides target proteins to the thylakoids.

Mitochondrial targeting peptide

The N-terminal mitochondrial targeting peptide (mtTP) allows for the protein to be imported into the mitochondrion.

Chloroplast targeting peptide

The N-terminal chloroplast targeting peptide (cpTP) allows for the protein to be imported into the chloroplast.

N-Terminal modifications

Some proteins are modified posttranslationally by the addition of membrane anchors that allow the protein to associate with membrane without having a transmembrane domain. The N-terminus (as well as the C-terminus) of a protein can be modified this way.

N-Myristoylation

The N-terminus can be modified by the addition of a myristoyl anchor. Proteins that are modified this way contain a consensus motif at their N-terminus as a modification signal.

N-Acylation

The N-terminus can also be modified by the addition of a fatty acid anchor to form N-acylated proteins. The most common form of such modification is the addition of a palmitoyl group.

N-Terminal acetylation

References

UpToDate Contents

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English Journal

Molecular cloning, tissue expression and regulation of nutrition and temperature on Δ6 fatty acyl desaturase-like gene in the red claw crayfish (Cherax quadricarinatus).

Wu DL1, Huang YH1, Liu ZQ1, Yu P1, Gu PH1, Fan B1, Zhao YL2.
Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology.Comp Biochem Physiol B Biochem Mol Biol.2018 Nov;225:58-66. doi: 10.1016/j.cbpb.2018.07.003. Epub 2018 Jul 17.
PMID 30030191

Doxorubicin conjugated with a trastuzumab epitope and an MMP-2 sensitive peptide linker for the treatment of HER2-positive breast cancer.

You Y1, Xu Z1, Chen Y1,2.
Drug delivery.Drug Deliv.2018 Nov;25(1):448-460. doi: 10.1080/10717544.2018.1435746.
PMID 29405790

Alternative splicing of (ppp1r12a/mypt1) in zebrafish produces a novel myosin phosphatase targeting subunit.

LaFlamme A1, Young KE1, Lang I1, Weiser DC2.
Gene.Gene.2018 Oct 30;675:15-26. doi: 10.1016/j.gene.2018.06.092. Epub 2018 Jun 28.
PMID 29960069

Japanese Journal

Enhancement of thermo-stability and product tolerance of Pseudomonas putida nitrile hydratase by fusing with self-assembling peptide(ENZYMOLOGY, PROTEIN ENGINEERING, AND ENZYME TECHNOLOGY)

Liu Yi,Cui Wenjing,Liu Zhongmei [他],Cui Youtian,Xia Yuanyuan,Kobayashi Michihiko,Zhou Zhemin
Journal of bioscience and bioengineering 118(3), 249-252, 2014-09
… It has been reported that the attachment of SAPs to the N- or C-terminus of an enzyme can benefit the thermo-stability of the enzyme. … When the ELK16 was fused to the N-terminus of β-subunit, the resultant NHase (SAP-NHase-2) became an active inclusion body; …
NAID 110009857352

Design and synthesis of fluorescent probes for GPR54.

Kaneda Masato,Misu Ryosuke,Ohno Hiroaki,Hirasawa Akira,Ieda Nahoko,Uenoyama Yoshihisa,Tsukamura Hiroko,Maeda Kei-ichiro,Oishi Shinya,Fujii Nobutaka
Bioorganic & medicinal chemistry 22(13), 3325-3330, 2014-07-01
… In this study, several fluorescent probes have been designed and synthesized for rat GPR54 through the modification of the N-terminus of rat kisspeptins to allow for the visualization of the expression and localization of kisspeptin receptor(s) in living cells and native tissues. …
NAID 120005466733

The N-terminus and Tudor domains of Sgf29 are important for its heterochromatin boundary formation function

Kamata Kazuma,Goswami Gayatri,Kashio Sayaka [他]
The journal of biochemistry 155(3), 159-171, 2014-03
NAID 40020021420

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