Synthesis of membrane lipids Most membrane lipids are synthesized enterly within the ER There are two exceptions (1) sphingomyelin and glycolipids, (begins in ER; completed in Golgi) (2)some of the unique lipids of the Mit and ChI membranes(themself) The membranes of different Organelles have markedly different lipids composition Transport by budding:ER→GC、Ly、PM Transport by phospholipid exchange proteins(PEP): ER-other organelles (including mit and ChI
❖Synthesis of membrane lipids ➢ Most membrane lipids are synthesized enterly within the ER. ➢ There are two exceptions: (1) sphingomyelin and glycolipids, (begins in ER; completed in Golgi); (2) some of the unique lipids of the Mit and Chl membranes (themself). ➢ The membranes of different 0rganelles have markedly different lipids composition. ▪ Transport by budding：ER→GC、Ly、PM ▪ Transport by phospholipid exchange proteins(PEP)：ER→other organelles （including Mit and Chl）
The role of phospholipid translocators in lipid bilayer synthesis A》 ER MEMBRANE (B)PLASMA MEMBRANE CYTOSOL CELL EXTERIOR lipid bilayer of asymmetric lipid endoplasmic bilayer of plasma reticulum membrane ER LUMEN CYTOSOL PHOSPHOLIPID SYNTHESIS DELIVERY OF ADDS TO CYTOSOLIC HALF NEW MEMBRANE OF THE BILAYER BY EXOCYTOSIS phospholipid 9 pl translocators 000000 Scramblase SCRAMBLASE CATALYZES FLIPPASE CATALYSES FLIPPING OF SPECIFIC ABC FLIPPING OF PHOSPHOLIPID MOLECULES PHOSPHOLIPIDS TO CYTOPLASMIC MONOLAYER transporter Family) symmetric growth of both halves of bilayer ∞∞∞ 00000000
The role of phospholipid translocators in lipid bilayer synthesis phospholipid translocators = Scramblase (ABC transporter Family)
B. Functions of the ser Synthesis of steroids in endocrine cells Detoxification of organic compounds in liver cells System of oxygenases---cytochrome p450 family release of glucose 6-phosphate in liver cells . Sequestration of Ca2+ Ca2+-ATPase
B. Functions of the sER ❖Synthesis of steroids in endocrine cells. ❖Detoxification of organic compounds in liver cells. System of oxygenases---cytochrome p450 family ❖Release of glucose 6-phosphate in liver cells. ❖Sequestration of Ca2+ . Ca2+ -ATPase
3. The structure and functions of Golgi complex A. The polarity of Golgi complex cis FACE Golgi vesicle cIS cisterna media/ cisterna trans cisterna trans network ITGN) ans FACE tubu cis Golgi (B) C 200nm
3. The structure and functions of Golgi complex A.The polarity of Golgi complex
Regional differences in membrane composition across the Golgi stack 生: 学机物 0.15um Figure 8 19 Regional differences in membrane compo- the medal cisternae. (c) The enzyme nucleoside diphos. sition across the Golgi stack. (a) Reduced osmium tetroxide phatase, which splits dinucleotides(.g, UDP) after they preferentially impregnates the cis cisternae of the golgi have donated their sugar, is preferentially localized in the lex. (b) The enzyme mannosidase Il, which is involved trans cisternae. (ac: From Robert S. Decker, 1 Cell Biol. 61: 603 a)Cis cisternae of Golgi complex: reduced osmium tetroxide(OsO4) b)Reaction for enzyme mannosidase Il, localized in the medial Reaction fo
a) Cis cisternae of Golgi complex: reduced osmium tetroxide(OsO4 ); b) Reaction for enzyme mannosidase II , localized in the medial; c) Reaction for enzyme nucleoside diphosphatase , localized in the trans cisternae. ❖Regional differences in membrane composition across the Golgi stack