Chapter 25 Protein trafficking 清苇大当
Chapter 25 Protein trafficking
25.1 Introduction 25.2 Oligosaccharides are added to proteins in the ER and Golgi 25.3 The Golgi stacks are polarized 25.4 Coated vesicles transport both exported and imported proteins 25.5 Different types of coated vesicles exist in each pathway 25.6 Cisternal progression occurs more slowly than vesicle movement 25.7 Vesicles can bud and fuse with membranes 25.8 SNAREs control targeting 25.9 The synapse is a model system for exocytosis 25.10 Protein localization depends on specific signals 25.11 ER proteins are retrieved from the Golgi 25.12 Brefeldin A reveals retrograde transport 25.13 Receptors recycle via endocytosis 25.14 Internalization signals are short and contain tyrosine 清苇大当
25.1 Introduction 25.2 Oligosaccharides are added to proteins in the ER and Golgi 25.3 The Golgi stacks are polarized 25.4 Coated vesicles transport both exported and imported proteins 25.5 Different types of coated vesicles exist in each pathway 25.6 Cisternal progression occurs more slowly than vesicle movement 25.7 Vesicles can bud and fuse with membranes 25.8 SNAREs control targeting 25.9 The synapse is a model system for exocytosis 25.10 Protein localization depends on specific signals 25.11 ER proteins are retrieved from the Golgi 25.12 Brefeldin A reveals retrograde transport 25.13 Receptors recycle via endocytosis 25.14 Internalization signals are short and contain tyrosine
25.1 Introduction Sorting signal is a motif in a protein (either a short sequence of amino acids or a covalent modification)that is required for it to be incorporated into vesicles that carry it to a specific destination. 清菜大当
Sorting signal is a motif in a protein (either a short sequence of amino acids or a covalent modification) that is required for it to be incorporated into vesicles that carry it to a specific destination. 25.1 Introduction
25.1 Introduction Figure 25.1 Proteins that enter the endoplasmic reticulum are Secreted proteins oass through nembrane transported to the Golgi and Transport between endosome and towards the plasma membrane. Transport of surface plasma proteins to plasma membrane Tran sport from Specific signals cause proteins trans Golgi to endosomes to be returned from the Golgi urther ations ocau Tran sport from endosomes to yosom es to the ER,to be retained in the through Golgi stac Golgi,to be retained in the ER resident plasma membrane,or to be ansport to Golgi proteinsretum to ER transported to endosomes and during s lysosomes.Proteins may be transported between the plasma membrane and endosomes. 清菜大兰
Figure 25.1 Proteins that enter the endoplasmic reticulum are transported to the Golgi and towards the plasma membrane. Specific signals cause proteins to be returned from the Golgi to the ER, to be retained in the Golgi, to be retained in the plasma membrane, or to be transported to endosomes and lysosomes. Proteins may be transported between the plasma membrane and endosomes. 25.1 Introduction
25.1 Introduction Veside release Vesicle tusion CYTOSOL Figure 25.2 Vesicles are CYTOSOL Vesicle contads released when they bud from arget membrane a donor compartment and are surrounded by coat proteins(left).During fusion, Coat is rem oved the coated vesicle binds to a esde buds trom mem brane target compartment,is uncoated,and fuses with the target membrane,releasing Veside is released its contents(right) 清菜大当
Figure 25.2 Vesicles are released when they bud from a donor compartment and are surrounded by coat proteins (left). During fusion, the coated vesicle binds to a target compartment, is uncoated, and fuses with the target membrane, releasing its contents (right). 25.1 Introduction
N-acetyl-glucosamine ●Mannose●Glucose 25.2 Oligosaccharides are added to proteins in Dolich the ER and Golgi ENDOPLASMIC RETICULUM Figure 25.3 An oligosaccharide e is formed on dolichol and Asparagine in target transferred by glycosyl transferase to asparagine of a target protein. 清菜大当 Glycoprotein
Figure 25.3 An oligosaccharide is formed on dolichol and transferred by glycosyl transferase to asparagine of a target protein. 25.2 Oligosaccharides are added to proteins in the ER and Golgi
N-acetyl-glucosamine Mannose●Glucose 25.2 Oligosaccharides are added to proteins in the HC-CHCNO ER and Golgi C=0 Figure 25.4 Sugars are ER glucosidases|&∥ removed in the ER in a fixed order,initially comprising 3 glucose and 1-4 mannose residues.This trimming ER mannosidase generates a high mannose oligosaccharide. High mannose oligosacchande 清菜大当
Figure 25.4 Sugars are removed in the ER in a fixed order, initially comprising 3 glucose and 1-4 mannose residues. This trimming generates a high mannose oligosaccharide. 25.2 Oligosaccharides are added to proteins in the ER and Golgi
Golgi mannosidase 25.2 Oligosaccharides are NH H HC-CH - added to proteins in the ER and Golgi Golgi N-acetyl- glucosamine transferase Figure 25.5 Processing for a complex oligosaccharide occurs in the Golgi and trims the original preformed unit to the Golgi mannosidase ll inner core consisting of 2 N-acetyl- glucosamine and 3 mannose residues. HC-CHa EndoH resistance Then further sugars can be added,in the C=0 order in which the transfer enzymes are Golgi enzymes add further residues encountered,to generate a terminal GalSialic acid region containing N-acetyl-glucosamine, HOCH-CN galactose,and sialic acid -08 nner cote Terminal region 清菜大兰
Figure 25.5 Processing for a complex oligosaccharide occurs in the Golgi and trims the original preformed unit to the inner core consisting of 2 N-acetylglucosamine and 3 mannose residues. Then further sugars can be added, in the order in which the transfer enzymes are encountered, to generate a terminal region containing N-acetyl-glucosamine, galactose, and sialic acid. 25.2 Oligosaccharides are added to proteins in the ER and Golgi
25.2 Oligosaccharides are added to proteins in the ER and Golgi transo Figure 25.6 The Golgi apparatus consists of a series of individual ￥0sG0lg membrane stacks. Photograph kindly R provided by Alain Rambourg. 清菜大当
Figure 25.6 The Golgi apparatus consists of a series of individual membrane stacks. Photograph kindly provided by Alain Rambourg. 25.2 Oligosaccharides are added to proteins in the ER and Golgi
25.2 Oligosaccharides are added to proteins in the ER and Golgi mannose-6-P receptors sialyl transterase N:(trans-Golgi netwo Figure 25.7 A Golgi acid phosphatase stack consists of a series galactosyl transferase of cisternae,organized with cis to trans polarity. 1P-NAc-glucosaminidase NADPase medial cistemna Protein modifications m annosidase ll occur in order as a glcN-acetyl-transferase mannosidase I protein moves from the 660cae cis face to the trans face. 清菜大兰
Figure 25.7 A Golgi stack consists of a series of cisternae, organized with cis to trans polarity. Protein modifications occur in order as a protein moves from the cis face to the trans face. 25.2 Oligosaccharides are added to proteins in the ER and Golgi