100nm Figure 8.6 The formation of coated vesicles in a cell -free system. Electron micrograph of a liposome preparation that
igure 8.7 The use of genetic mutants in the study ofsecre- ion (a)Schematic drwing of the hirst leg of the biosynthetic eactory pathway in the budding yeast( Sachronaes cere a). The steps are described below. (A)Electron microg fascction through a wild-type veast cell containing a small mount of endoplasmic reticulum (ER). ( A yeast cell bearing mutation in the sec12 gene whose product is involved in the marion of vesicles at the ER membrane(step 1, part a). Be- Vesicle msevesicles cannot form, expanded ER cisternae accumulate Vesicle athe cell () A yeast cell bcaring a mutation in the ser/? gene. hose product is involved in vesicle fusion(step 2, part a). Be- use they cannot fuse with Golgi membranes. the vesicles (in cited by the arrowheads)accumulate in the cell.The m- tats depicted in c and d are temperature-sensitive mutants page 283). As long as they are kept at the lower(permissive) hey are capable of normal growth and division.) sOM CHRIS A KASER AND R IN SIIEKS1A\, CIL 61: 724 1 N) EE\ 家理 RAnSSLONO CELL PRESS.)
8.3 Structues and funcions of the major organelles of eMs 8.3.1 The endoplasmic reticulum (Er) 1. Outline Early it is called ergastoplasm, it was shown in pancreatic cells as basephilic and related to protein synthesis depending on physiological condition. 1952, K Porter observate its network ultrastructure on in vitro fibroblasts. and refered as the endoplasmic reticum(ER) 1)Structure and composition It comprises a vary complex system of thiner membranes (5-6 nm) that enclose a space or lumen or Cisternal space, with a dynamic changed-shape with physiologic state:, flattened sacs vesicles and tubules( 40-70 nm) with branchs It is divided into two broad categories or parts: Ro ou h endoplasmic reticulum(RER)attached ribosomes and a smooth endoplasmic reticulum (SER) without ribosomes, the former is typically extensive flattened sacs stacks, the later is typically tubules and form interconnecting system
8.3 Structues and funcions of the major organelles of EMS 8.3.1 The endoplasmic reticulum (ER) 1. Outline Early it is called ergastoplasma, it was shown in pancreatic cells as basephilic and related to protein synthesis depending on physiological condition. 1952, K Porter observate its network ultrastructure on in vitro fibroblasts, and refered as the endoplasmic reticum (ER). 1) Structure and composition It comprises a vary complex system of thiner membranes (5-6 nm) that enclose a space or lumen or Cisternal space, with a dynamic changed-shape with physiologic state:, flattened sacs, vesicles and tubules ( 40-70 nm) with branchs It is divided into two broad categrories or parts: Rough endoplasmic reticulum(RER) attached ribosomes and a smooth endoplasmic reticulum(SER) without ribosomes, the former is typically extensive flattened sacs stacks, the later is typically tubules and form interconnecting system
Ribosome Tubular endoplasmic reticulum x· Cisternae of endoplasmic reticulum Vesicular endoplasmic ticulum
Its membrane composition: higher amount of proteins, less cholesterol than plasma membrane, 23 PLs per protein Eg for Rat liver cell, Protein 60-70%, PL 30-40%( PC 55%,PE20-25%,PS5-10%,PI5-10% and sph4-7% In er. there are 30-40 enzymes among them. Marker enzymes: are cytochrome p 450, glucose-6-phosphatase 义力HH,: 表42各种ER酶在ER膜的横向分布 酶 表面位置 酶 表面位置 细胞色素bs 细胞质面 核苷焦磷酸酶 细胞质面 NADH细胞色素b还原酶细胞质面 GDP-甘露糖基转移酶 细胞质面 NADH细胞色素c还原酶细胞质面 核苷二磷酸酶 腔面 细胞色素P450 细胞质面、腔面葡萄糖6磷酸酶腔面 ATP酶 细胞质面 乙酰苯胺-水解酯酶 腔面 5′-核苷酸酶 细胞质面 B-葡糖苷酸酶 腔面 引自 Neal o. Thorpe,1984) 内质网膜上特异的Ca2- ATPase能把胞内游离Ca2泵入内质网腔内,同时又存在 IP3受体和 Ryanodine受体钙通道,在IP3或 Ryanodine作用下,相应的钙通道被打 开,Ca2释放到胞浆
Its membrane composition: higher amount of proteins, less cholesterol than plasma membrane, 23 PLs per protein. Eg. for Rat liver cell, Protein ~ 60-70%, PL ~30-40% ( PC 55%, PE 20-25%, PS 5-10%, PI 5-10% and Sph 4-7%. In ER, there are 30-40 enzymes, among them, Marker enzymes: are cytochrome p 450, glucose-6-phosphatase. 内质网膜上特异的Ca2+－ATPase能把胞内游离Ca2+泵入内质网腔内，同时又存在 IP3受体和Ryanodine受体钙通道，在IP3或Ryanodine作用下，相应的钙通道被打 开， Ca2+释放到胞浆