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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

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目的,終結 / (鉄道・バスの)終点,終着駅

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/10/09 12:22:44」(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).

The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is translated from messenger RNA, it is created from N-terminus to C-terminus. The convention for writing peptide sequences is to put the C-terminal end on the right and write the sequence from N- to C-terminus.

Chemistry[edit]

Each amino acid has a carboxyl group and an amine group, and amino acids link to one another to form a chain by a dehydration reaction by joining the amine group of one amino acid to the carboxyl group of the next. Thus polypeptide chains have an end with an unbound carboxyl group, the C-terminus, and an end with an amine group, the N-terminus. Proteins are naturally synthesized starting from the N-terminus and ending at the C-terminus.

Function[edit]

C-terminal retention signals[edit]

While the N-terminus of a protein often contains targeting signals, the C-terminus can contain retention signals for protein sorting. The most common ER retention signal is the amino acid sequence -KDEL (or -HDEL) at the C-terminus, which keeps the protein in the endoplasmic reticulum and prevents it from entering the secretory pathway.

C-terminal modifications[edit]

The C-terminus of proteins can be modified posttranslationally, most commonly by the addition of a lipid anchor to the C-terminus that allows the protein to be inserted into a membrane without having a transmembrane domain.

Prenylation[edit]

Main article: Prenylation

One form of C-terminal modification is prenylation. During prenylation, a farnesyl- or geranylgeranyl-isoprenoid membrane anchor is added to a cysteine residue near the C-terminus. Small, membrane-bound G proteins are often modified this way.

GPI anchors[edit]

Main article: Glycosylphosphatidylinositol

Another form of C-terminal modification is the addition of a phosphoglycan, glycosylphosphatidylinositol (GPI), as a membrane anchor. The GPI anchor is attached to the C-terminus after proteolytic cleavage of a C-terminal propeptide. The most prominent example for this type of modification is the prion protein.

C-terminal domain[edit]

RNA POL II in action.

The C-terminal domain (or carboxyl tail domain, CTD) of some proteins has specialized functions. The CTD of RNA polymerase II typically consists of up to 52 repeats of the sequence Tyr-Ser-Pro-Thr-Ser-Pro-Ser.^[1] Other proteins often bind the C-terminal domain of RNA polymerase in order to activate polymerase activity. It is the protein domain which is involved in the initiation of DNA transcription, the capping of the RNA transcript, and attachment to the spliceosome for RNA splicing.^[2]

References[edit]

^ Meinhart A, Cramer P (July 2004). "Recognition of RNA polymerase II carboxy-terminal domain by 3'-RNA-processing factors". Nature 430 (6996): 223–6. doi:10.1038/nature02679. PMID 15241417.
^ Brickey WJ, Greenleaf AL (June 1995). "Functional studies of the carboxy-terminal repeat domain of Drosophila RNA polymerase II in vivo". Genetics 140 (2): 599–613. PMC 1206638. PMID 7498740.

UpToDate Contents

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1. ペプチドホルモンのシグナル伝達および調節 peptide hormone signal transduction and regulation
2. インスリン受容体の構造および機能 structure and function of the insulin receptor
3. プリオンの生物学および遺伝学 biology and genetics of prions
4. 白血球増多症および好中球増多症の定義およびメカニズム definition and mechanisms of leukocytosis and neutrophilia
5. 肝臓の合成能の検査（アルブミン、凝固因子、プロトロンビン時間など） tests of the livers biosynthetic capacity eg albumin coagulation factors prothrombin time

English Journal

The hydrophobic amino acids in putative helix 8 in carboxy-terminus of histamine H(3) receptor are involved in receptor-G-protein coupling.

Kuramasu A, Sukegawa J, Sato T, Sakurai E, Watanabe T, Yanagisawa T, Yanai K.SourceDepartment of Pharmacology, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8575, Japan. atsuok@yamaguchi-u.ac.jp
Cellular signalling.Cell Signal.2011 Nov;23(11):1843-9. Epub 2011 Jul 3.
Functional roles of putative helix 8 in the carboxy-terminal tail of the human histamine H(3) receptor were investigated using deleted and alanine-substituted mutant receptors. While the deletion of the carboxy-terminal tail did not decrease the total expression level, surface expression, or ligand
PMID 21749919

Motor neuron impairment mediated by a sumoylated fragment of the glial glutamate transporter EAAT2.

Foran E, Bogush A, Goffredo M, Roncaglia P, Gustincich S, Pasinelli P, Trotti D.SourceWeinberg Unit for ALS Research, Department of Neuroscience, Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
Glia.Glia.2011 Nov;59(11):1719-31. doi: 10.1002/glia.21218. Epub 2011 Jul 18.
Dysregulation of glutamate handling ensuing downregulation of expression and activity levels of the astroglial glutamate transporter EAAT2 is implicated in excitotoxic degeneration of motor neurons in amyotrophic lateral sclerosis (ALS). We previously reported that EAAT2 (a.k.a. GLT-1) is cleaved by
PMID 21769946

Japanese Journal

Peptide Ligation Using a Building Block Having a Cysteinyl Prolyl Ester (CPE) Autoactivating Unit at the Carboxy Terminus

KAWAKAMI Toru,AIMOTO Saburo
Chemistry letters 36(1), 76-77, 2007-01-05
NAID 10018663050

Gタンパク質共役型受容体機能の会合タンパク質による調節(誌上シンポジウム)

中畑則道,斎藤将樹
藥學雜誌 127(1), 3-14, 2007-01-01
… G protein-coupled receptors (GPCRs) are seven transmembrane receptors with an N-terminus in the extracellular region and C-terminus in the intracellular region. … One of the mechanisms is regulation through the binding proteins to the carboxy (C)-terminus of GPCRs. …
NAID 110006155005