Copyright (c) by W. H. Freeman and Company 17.3 The rough ER is an extensive interconnected series of flattened sacs Figure 17-11

Copyright (c) by W. H. Freeman and Company

17.3 The rough ER is an extensive interconnected series of flattened sacs

Figure 17-11


17.3 Secretory proteins are found in the ER lumen immediately after synthesis

Figure 17-12


17.3 Overview of the secretory pathway

Figure 17-13

cisternalprogression


17.3 Many experiments on the secretory pathway have relied on cells specialized for the secretion of certain proteins


Box 4.5


17.3 Analysis of yeast mutants defined the major steps in the secretory pathway

Figure 17-14


Fig. 4.13


Fig. 4.14


17.4 A signal sequence on nascent secretory proteins targets them to the ER and then is cleaved off


17.4 The cotranslational import of proteins into the ER is studied with microsomes

Figure 17-15


17.3 Some acronyms

SRP - signal recognition particle Particle made of 1 RNA and six proteins which binds the signal sequence on newly made proteins

SRP receptor - ER protein which binds SRPTRAM - translocating chain-associated

membrane (also translocon) takes the protein across the ER membrane


17.4 Two proteins initiate the interaction of signal sequences with the ER membrane

Figure 17-16


17.4 Structure of the signal recognition particle (SRP)

Figure 17-17


17.4 Polypeptides move through the translocon into the ER lumen

Figure 17-18


Fig. 4.15


17.4 GTP hydrolysis powers protein transport into the ER in mammalian cells

Figure 17-20


17.5 Topologies of some integral membrane proteins synthesized on the rough ER

Figure 17-21


Fig. 4.17


17.5 Most nominal cytosolic transmembrane proteins have an N-terminal signal sequence and an internal topogenic sequence

Figure 17-22


17.5 A single internal topogenic sequence directs insertion of some single-pass transmembrane proteins

Figure 17-23


17.5 Multipass transmembrane proteins have multiple topogenic sequences

Figure 17-24


17.5 After insertion into the ER membrane, some proteins are transferred to a GPI anchor

Figure 17-25


17.5 After insertion into the ER membrane, some proteins are transferred to a GPI anchor

Figure 17-25


17.6 Post-translational modifications and quality control in the rough ER

Newly synthesized polypeptides in the membrane and lumen of the ER undergo five principal modifications Formation of disulfide bonds Proper folding Addition and processing of carbohydrates Specific proteolytic cleavages Assembly into multimeric proteins


17.6 Disulfide bonds are formed and rearranged in the ER lumen

Figure 17-26


Fig. 4.18


17.6 Correct folding of newly made proteins is facilitated by several ER proteins

Figure 17-27


17.6 ER-resident proteins often are retrieved from the cis-Golgi

Figure 17-29


17.7 Different structures characterize N- and O-linked oligosaccharides

Figure 17-30


17.7 The immediate precursors in the synthesis of oligosaccharides are nucleoside diphosphate or monophosphate sugars

Figure 17-31


17.7 Specific sugars are linked by specific glycosyltransferases

Figure 17-32


17.7 Sugar nucleotides and free nucleotides are exchanged by antiporters in the ER membrane

Figure 17-33


17.7 ABO blood type is determined by two glycosyltransferases

Figure 17-34


17.7 ABO blood groups


17.7 A common preformed N-linked oligosaccharide is added to many proteins in the rough ER

Figure 17-35


17.7 Addition and initial processing of N-linked oligosaccharides in the rough ER

Figure 17-36


Fig. 4.27


Fig. 4.20


Fig. 4.28


Fig. 4.22


Box 4.4


Fig. 4.23Developing wheat endosperm


Fig. 4.24


Fig. 4.25


Fig. 4.29extensin


17.7 Modifications to N-linked oligosaccharides are completed in the Golgi complex

Figure 17-38

Oligosaccharides may promote folding and stability of glycoproteins


Golgi and post-Golgi protein sorting

Sequences in the membrane-spanning domain cause the retention of proteins in the Golgi

Different vesicles are used for continuous and regulated protein secretion

Copyright (c) by W. H. Freeman and Company Fig. 4.21


17.10 Components that participate in budding of coated vesicles

Figure 17-51


Figure 17-60


17.10 A clathrin-coated pit on the cytosolic face of the plasma membrane

Figure 17-35


17.10 Structure of a clathrin-coated vesicle

Figure 17-53


17.10 Model for formation of a clathrin-coated pit and selective incorporation of integral membrane proteins

Figure 17-54


17.10 GTP hydrolysis by dynamin is required for pinching off of clathrin-coated vesicles

Figure 17-55


17.10 COP I vesicles mediate retrograde transport within the Golgi and from the Golgi back to the ER

Figure 17-56


17.10 Model for formation of COP I-coated vesicles

Figure 17-58


17.10 Specific fusion of intracellular vesicles involves a conserved set of fusion proteins

Figure 17-59


Box 4.6B

Documents

Copyright (c) by W. H. Freeman and Company 17.3 The rough ER is an extensive interconnected series of flattened sacs Figure 17-11