Lipid Metabolism

Lipids are omnipresent in a multitude of vital cell processes. Cells use lipids to store energy, build membranes, signal within and between cells, sense the environment, covalently modify proteins, form specialized permeability barriers (e.g., in skin), and protect cells from highly reactive chemicals.

To utilize lipids available from food, adipose tissue or synthesis by the liver, a complex transport system for lipids, primarily in the form of triglycerides has been established. Lipoproteins enable cells to transport hydrophobic lipid molecules via the aqueous blood and tissue lymph environment. Lipoprotein particles are defined by their complement of associated apolipoproteins (Apo) and their content of cholesterol (CHOL), triglyceride (TG) and phospholipid that each particle carries. Specific apolipoprotein constituents control the lipoprotein metabolism and are involved in the transport and redistribution of lipids among various cells and tissues.

Lipoproteins have been grouped into four major classes: high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), and chylomicrons1. First step to form HDL is the transfer of cholesterol and phospholipids onto apolipoproteinA-1 (ApoA-1) to generate nascent HDL. NPC1 is responsible for the intracellular transport of cholesterol, the transfer to HDL is catalysed by the ATP-binding cassette (ABC) A1 (ABCA1) transporter 2. ABCG1, another ABC transporter, is able to load more cholesterol onto HDL from peripheral tissues as well as intestines (dietary cholesterol) which is then esterified by Lysolecithin cholesterol acyltransferase (LCAT) in order to generate the mature HDL3. HDL cholesterol-esters are taken up by scavenger receptor SCARB1 in liver and after hydrolysis the resulting free cholesterol is metabolized to bile acids (BA). The bile acids are excreted into the digestive tract in a process that again utilizes ABC transporters (ABCG5/ABCG8, ABC11, ABCB4 and ABCC2).

In the small intestine absorbed dietary fatty acids are converted into TGs and together with ApoB, ApoE and ApoC2 subsequently packaged and secreted into the bloodstream as chylomicrons. Lipoprotein lipase (LPL) hydrolizes the TG, and chylomicron remnants emerge, which are taken up by the liver via the apoE receptor (ApoER). Cholesterol ester from HDL are also transferred to VLDL remnant particles (IDL) via the cholesteryl ester transfer protein (CETP)4. IDL on the other hand loses the majority of apolipoprotein and is converted to LDL by the action of hepatic lipase (LIPC). This converts IDL into LDL, which is taken up by cells that require cholesterol for incorporation into their cell membranes or for synthetic purposes (e.g. the formation of the steroid hormones). The remainder of the LDLs is removed by the liver. Uptake is mediated by SCARB3 (also known as CD36) and LDL receptor (LDLR) in both cases. Proprotein convertase subtilisin/kexin type 9 (PCSK9) can bind and inhibit the LDLR.


References:

  1. Braiman, A and Isakov, N (2009): "Triglycerides and HDL Cholesterol”. Diabetes Care., S373–S377.[PMID: 2811435]
  2. Gong x (2016): “Structural Insights into the Niemann-Pick C1 (NPC1)-Mediated Cholesterol Transfer and Ebola Infection.” Cell, 165(6):1467-1478. [PMID: 27238017]
  3. Rousset (2009): “Lecithin:Cholesterol Acyltransferase: From Biochemistry to Role in Cardiovascular Disease”. Curr Opin Endocrinol Diabetes Obes, 16(2): 163–171. [PMID: 2910390]
  4. Zhang (2015): “HDL surface lipids mediate CETP binding as revealed by electron microscopy and molecular dynamics simulation”. Sci Rep, 5: 8741. [PMID: 4348656]


Apolipoproteine

APOA1 - Apolipoprotein A-I

This gene encodes apolipoprotein A-I, which is the major protein component of high density lipoprotein (HDL) in plasma. The protein promotes cholesterol efflux from tissues to the liver for excretion, and it is a cofactor for lecithin cholesterolacyltransferase (LCAT) which is responsible for the formation of most plasma cholesteryl esters. This gene is closely linked with two other...   更多...

APOE (Apolipoprotein E):

此分类里的别的抗原:
APOC4 (Apolipoprotein C-IV): APOC4 抗体 APOC4 ELISA试剂盒 APOC4 蛋白
ApoE3 (Apolipoprotein E3): ApoE3 抗体 ApoE3 ELISA试剂盒  
APOA5 - Apolipoprotein A-V: APOA5 抗体 APOA5 ELISA试剂盒 APOA5 蛋白
APOB (Apolipoprotein B): APOB 抗体 APOB ELISA试剂盒 APOB 蛋白
APOA2 - Apolipoprotein A-II: APOA2 抗体 APOA2 ELISA试剂盒 APOA2 蛋白
APOC3 (Apolipoprotein C-III): APOC3 抗体 APOC3 ELISA试剂盒 APOC3 蛋白
APOC2 - Apolipoprotein C-II: APOC2 抗体 APOC2 ELISA试剂盒 APOC2 蛋白
APOA4 (Apolipoprotein A-IV): APOA4 抗体 APOA4 ELISA试剂盒 APOA4 蛋白

ATP-Binding Cassette

此分类里的别的抗原:
ABCG1 (ATP-Binding Cassette, Sub-Family G (WHITE), Member 1): ABCG1 抗体 ABCG1 ELISA试剂盒 ABCG1 蛋白
ABCA1 (ATP-Binding Cassette, Sub-Family A (ABC1), Member 1): ABCA1 抗体 ABCA1 ELISA试剂盒 ABCA1 蛋白
ABCG5 (ATP-Binding Cassette, Sub-Family G (WHITE), Member 5): ABCG5 抗体 ABCG5 ELISA试剂盒 ABCG5 蛋白
ABCG8 (ATP-Binding Cassette, Sub-Family G (WHITE), Member 8): ABCG8 抗体   ABCG8 蛋白

Lipase & Protease & Inhibitors

此分类里的别的抗原:
ABHD5 (Abhydrolase Domain Containing 5): ABHD5 抗体 ABHD5 ELISA试剂盒 ABHD5 蛋白
ANG - Angiostatin: ANG 抗体 ANG ELISA试剂盒 ANG 蛋白
GIP (Gastric Inhibitory Polypeptide): GIP 抗体 GIP ELISA试剂盒 GIP 蛋白
A2M - alpha 2 Macroglobulin: A2M 抗体 A2M ELISA试剂盒 A2M 蛋白
LCAT (Lecithin-Cholesterol Acyltransferase): LCAT 抗体 LCAT ELISA试剂盒 LCAT 蛋白
(Cholesterol Esterase):      
MGLL (Monoglyceride Lipase): MGLL 抗体 MGLL ELISA试剂盒 MGLL 蛋白
PLG (Plasminogen): PLG 抗体 PLG ELISA试剂盒 PLG 蛋白
PSMB3 - Proteasome (Prosome, Macropain) Subunit, beta Type, 3: PSMB3 抗体   PSMB3 蛋白
CLPS - Colipase, Pancreatic: CLPS 抗体 CLPS ELISA试剂盒 CLPS 蛋白
PNLIPRP2 - Pancreatic Lipase-Related Protein 2: PNLIPRP2 抗体 PNLIPRP2 ELISA试剂盒 PNLIPRP2 蛋白
LIPE (Lipase, Hormone-Sensitive): LIPE 抗体 LIPE ELISA试剂盒 LIPE 蛋白
LIPC - Lipase, Hepatic: LIPC 抗体 LIPC ELISA试剂盒 LIPC 蛋白
LPL - Lipoprotein Lipase: LPL 抗体 LPL ELISA试剂盒 LPL 蛋白

Lipidtransport

此分类里的别的抗原:
PLTP (Phospholipid Transfer Protein): PLTP 抗体 PLTP ELISA试剂盒 PLTP 蛋白
PLIN1 (Perilipin 1): PLIN1 抗体 PLIN1 ELISA试剂盒 PLIN1 蛋白
HSPG2 (Heparan Sulfate Proteoglycan 2): HSPG2 抗体 HSPG2 ELISA试剂盒 HSPG2 蛋白
P4HB - PDI: P4HB 抗体 P4HB ELISA试剂盒 P4HB 蛋白
ALB - Albumin: ALB 抗体 ALB ELISA试剂盒 ALB 蛋白
BSA - Bovine Serum Albumin: BSA 抗体 BSA ELISA试剂盒 BSA 蛋白
SAR1B (SAR1 Homolog B (S. Cerevisiae)): SAR1B 抗体   SAR1B 蛋白

Protein Kinase & Protein Phosphatase

此分类里的别的抗原:
PRKACB (Protein Kinase, CAMP Dependent, Catalytic, beta): PRKACB 抗体 PRKACB ELISA试剂盒 PRKACB 蛋白
PP1-BETA - Serine/threonine-Protein Phosphatase PP1-beta Catalytic Subunit: PP1-BETA 抗体    
PPP1CB - Protein Phosphatase 1, Catalytic Subunit, beta Isoform: PPP1CB 抗体   PPP1CB 蛋白
ABL1 (C-Abl Oncogene 1, Non-Receptor tyrosine Kinase): ABL1 抗体 ABL1 ELISA试剂盒 ABL1 蛋白
PRKACA (Protein Kinase A, alpha): PRKACA 抗体 PRKACA ELISA试剂盒 PRKACA 蛋白
PPP1CC - Protein Phosphatase 1, Catalytic Subunit, gamma Isoform: PPP1CC 抗体   PPP1CC 蛋白
PPP1CA - Protein Phosphatase 1, Catalytic Subunit, alpha Isoform: PPP1CA 抗体 PPP1CA ELISA试剂盒 PPP1CA 蛋白
PKCd - PKC delta: PKCd 抗体 PKCd ELISA试剂盒 PKCd 蛋白
PRKACG (Protein Kinase, CAMP-Dependent, Catalytic, gamma): PRKACG 抗体   PRKACG 蛋白

Receptors & Signalling

此分类里的别的抗原:
AMN (Amnionless): AMN 抗体 AMN ELISA试剂盒 AMN 蛋白
TFAP2A (Transcription Factor AP-2 alpha (Activating Enhancer Binding Protein 2 Alpha)): TFAP2A 抗体 TFAP2A ELISA试剂盒 TFAP2A 蛋白
BMP1 (Bone Morphogenetic Protein 1): BMP1 抗体 BMP1 ELISA试剂盒 BMP1 蛋白
LDLR (Low Density Lipoprotein Receptor): LDLR 抗体 LDLR ELISA试剂盒 LDLR 蛋白
SCARB1 (Scavenger Receptor Class B, Member 1): SCARB1 抗体 SCARB1 ELISA试剂盒 SCARB1 蛋白
CD36 (CD36 Molecule (thrombospondin Receptor)): CD36 抗体 CD36 ELISA试剂盒 CD36 蛋白
CUBN (Cubilin (Intrinsic Factor-Cobalamin Receptor)): CUBN 抗体 CUBN ELISA试剂盒 CUBN 蛋白
SDC1 - Syndecan 1: SDC1 抗体 SDC1 ELISA试剂盒 SDC1 蛋白
LDLRAP1 (Low Density Lipoprotein Receptor Adaptor Protein 1): LDLRAP1 抗体 LDLRAP1 ELISA试剂盒 LDLRAP1 蛋白