関: apo A、apoA

WordNet

the 1st letter of the Roman alphabet (同)a
the blood group whose red cells carry the A antigen (同)type_A, group A

PrepTutorEJDIC

answer / ampere
arsenic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）』「2014/03/27 16:39:02」(JST)

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Apolipoproteins are proteins that bind lipids (oil-soluble substances such as fat and cholesterol) to form lipoproteins. They transport the lipids through the lymphatic and circulatory systems.

The lipid components of lipoproteins are insoluble in water. However, because of their detergent-like (amphipathic) properties, apolipoproteins and other amphipathic molecules (such as phospholipids) can surround the lipids, creating the lipoprotein particle that is itself water-soluble, and can thus be carried through water-based circulation (i.e., blood, lymph).

Apolipoproteins also serve as enzyme cofactors, receptor ligands, and lipid transfer carriers that regulate the metabolism of lipoproteins and their uptake in tissues.

Functions[edit]

In lipid transport, apolipoproteins function as structural components of lipoprotein particles, cofactors for enzymes and ligands for cell-surface receptors. In particular, apoA1 is the major protein component of high-density lipoproteins; apoA4 is thought to act primarily in intestinal lipid absorption. Further, apoE is a blood plasma protein that mediates the transport and uptake of cholesterol and lipid by way of its high affinity interaction with different cellular receptors, including the low-density lipoprotein (LDL) receptor. Recent findings with apoA1 and apoE suggest that the tertiary structures of these two members of the human exchangeable apolipoprotein gene family are related.^[1] The three-dimensional structure of the LDL receptor-binding domain of apoE indicates that the protein forms an unusually elongated four-helix bundle that may be stabilised by a tightly packed hydrophobic core that includes leucine zipper-type interactions and by numerous salt bridges on the mostly charged surface. Basic amino acids important for LDL receptor binding are clustered into a surface patch on one long helix.^[2]

They are enzyme coenzymes (C-II for lipoprotein lipase and A-I for lecithin-cholesterol acyltransferase)
Lipid transport proteins
Ligands for interaction with lipoprotein receptors in tissues ( apoB100 and apoE for LDL-receptors, apoA-I for HDL receptors)

Classes[edit]

There are two major types of apolipoproteins. Apolipoproteins B form low-density lipoprotein ("bad cholesterol") particles. These proteins have mostly beta-sheet structure and associate with lipid droplets irreversibly. Other apolipoproteins form high-density lipoprotein ("good cholesterol") particles. These proteins consist of alpha-helices and associate with lipid droplets reversibly. During binding to the lipid particles these proteins change their three-dimensional structure.

There are six classes of apolipoproteins and several sub-classes:

A (apo A-I, apo A-II, apo A-IV, and apo A-V)
B (apo B48 and apo B100)
C (apo C-I, apo C-II, apo C-III, and apo C-IV)
D
E
H

Exchangeable apolipoproteins (apoA, apoC and apoE) have the same genomic structure and are members of a multi-gene family that probably evolved from a common ancestral gene. ApoA1 and ApoA4 are part of the APOA1/C3/A4/A5 gene cluster on chromosome 11.^[3]

Hundreds of genetic polymorphisms of the apolipoproteins have been described, and many of them alter their structure and function.

Synthesis and regulation[edit]

Apolipoprotein synthesis in the intestine is regulated principally by the fat content of the diet.

Apolipoprotein synthesis in the liver is controlled by a host of factors, including dietary composition, hormones (insulin, glucagon, thyroxin, estrogens, androgens), alcohol intake, and various drugs (statins, niacin, and fibric acids). Apo B is an integral apoprotein whereas the others are peripheral apoproteins.

References[edit]

^ Saito H, Lund-Katz S, Phillips MC (July 2004). "Contributions of domain structure and lipid interaction to the functionality of exchangeable human apolipoproteins". Prog. Lipid Res. 43 (4): 350–80. doi:10.1016/j.plipres.2004.05.002. PMID 15234552.
^ Wilson C, Wardell MR, Weisgraber KH, Mahley RW, Agard DA; Wardell; Weisgraber; Mahley; Agard (June 1991). "Three-dimensional structure of the LDL receptor-binding domain of human apolipoprotein E". Science 252 (5014): 1817–22. Bibcode:1991Sci...252.1817W. doi:10.1126/science.2063194. PMID 2063194.
^ Fullerton SM, Buchanan AV, Sonpar VA, Taylor SL, Smith JD, Carlson CS, Salomaa V, StengÃ¥rd JH, Boerwinkle E, Clark AG, Nickerson DA, Weiss KM (June 2004). "The effects of scale: variation in the APOA1/C3/A4/A5 gene cluster". Hum. Genet. 115 (1): 36–56. doi:10.1007/s00439-004-1106-x. PMID 15108119.

External links[edit]

HuGENet Review
Apolipoprotein AI Mutations and Information

This article incorporates text from the public domain Pfam and InterPro IPR000074

UpToDate Contents

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English Journal

Proteasomal Inhibition Promotes ATP-Binding Cassette Transporter A1 (ABCA1) and ABCG1 Expression and Cholesterol Efflux From Macrophages In Vitro and In Vivo.

Ogura M, Ayaori M, Terao Y, Hisada T, Iizuka M, Takiguchi S, Uto-Kondo H, Yakushiji E, Nakaya K, Sasaki M, Komatsu T, Ozasa H, Ohsuzu F, Ikewaki K.SourceDivisions of Anti-aging and Cardiology, Department of Internal Medicine, National Defense Medical College, Tokorozawa, Japan.
Arteriosclerosis, thrombosis, and vascular biology.Arterioscler Thromb Vasc Biol.2011 Aug 4. [Epub ahead of print]
OBJECTIVE: ATP-binding cassette transporter A1 (ABCA1) and ABCG1 are key molecules in an initial step of reverse cholesterol transport (RCT), a major antiatherogenic property of high-density lipoprotein (HDL). The ubiquitin-proteasome system (UPS) mediates nonlysosomal pathways for protein degradati
PMID 21817095

Modified magnesium and lipoproteins in children with attention deficite hyperactivity disorder (ADHD).

Irmisch G, Thome J, Reis O, Hasler F, Weirich S.SourceDepartment of Psychiatry and Psychotherapy, Rostock University.
The world journal of biological psychiatry : the official journal of the World Federation of Societies of Biological Psychiatry.World J Biol Psychiatry.2011 Aug 3. [Epub ahead of print]
Abstract Objective. Polyunsaturated fatty acids (PUFAs) have shown to be helpful in the therapy of ADHD. Various stabilizing co-factors may contribute to this effect, as like magnesium (Mg). Mg supports fatty acid enzyme activity and is essential for the neuronal activity. However, the way of Mg to
PMID 21812620

Japanese Journal

Obesity-Related Mechanism of Food Intake Suppression

He Junfeng,Wong Siew Sun,Qu Yating,Xie Menzhou
Journal of brain science 36, 61-80, 2011-03-30
… In this article, leptin, insulin, melanocortin receptor, dopamine, serotonin, norepinephrine, brain-derived neurotrophic factor, cannabinoid-1 receptor blocker, cytokines, tumor necrosis factor-alpha, lipopolysaccharide, interleukin, cholecystokinin, enterostatin, estrogen, testosterone and apolipoprotein E will be discussed. …
NAID 110008574016

Molecular genetic epidemiology of homozygous familial hypercholesterolemia in the Hokuriku district of Japan

Mabuchi Hiroshi,Nohara Atsushi,Noguchi Tohru,Kobayashi Junji,Kawashiri Masaaki,Tada Hayato,Nakanishi Chiaki,Mori Mika,Yamagishi Masakazu,Inazu Akihiro,Koizumi Junji,Hokuriku FH Study Group
Atherosclerosis 214(2), 404-407, 2011-02
… Aim: Familial hypercholesterolemia (FH) is caused by mutations of FH genes, i.e. LDL-receptor (LDLR), PCSK9 and apolipoprotein B (ApoB) gene. …
NAID 120002924857

Related Pictures

★リンクテーブル★

リンク元	「アポリポタンパク質A」「アポリポ蛋白A」「アポリポ蛋白質A」「アポリポタンパクA」「apoA」
拡張検索	「apolipoprotein A-II」「apolipoprotein A-I」「apolipoprotein A2」
関連記事	「apolipoprotein」「A」「Ad」「apolipoproteins」

「アポリポタンパク質A」

Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe; PDBj
PDBsum	structure summary

Apolipoprotein
	; apolipoprotein e3 (apoe3)
Identifiers
Symbol	Apolipoprotein
Pfam	PF01442
InterPro	IPR000074
SCOP	1oef
SUPERFAMILY	1oef
OPM superfamily	193
OPM protein	3r2p
Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe; PDBj
PDBsum	structure summary