Chapter 13, Problem 9P

Summary Introduction

To explain: Which component does the KDEL receptor bind its ligand more tightly and more weakly.

Concept introduction: The retrieval pathway is a pathway that balances the flow of membrane between components. This work in opposite direction of secretory pathway and endocytic pathway bringing membrane proteins and some selected proteins back to its original component. The transports vesicles continually bud off from one membrane and fuse with another membrane. This carries forward the membrane components and soluble molecules. The secretory pathways work from endoplasmic reticulum (ER) to Golgi apparatus and to cell surface. The endocytic pathway works from plasma membrane to Golgi apparatus and to ER. The retrieval pathway in either case brings back the original components. KDEL is an ER retrieval signal that is important for a protein to retain in the ER lumen.

Summary Introduction

To explain: The reason for the KDEL receptor different binding affinities in the two compartments.

Concept introduction: The retrieval pathway is a pathway that balances the flow of membrane between components. This work in opposite direction of secretory pathway and endocytic pathway bringing membrane proteins and some selected proteins back to its original component. The transports vesicles continually bud off from one membrane and fuse with another membrane. This carries forward the membrane components and soluble molecules. The secretory pathways work from endoplasmic reticulum (ER) to Golgi apparatus and to cell surface. The endocytic pathway works from plasma membrane to Golgi apparatus and to ER. The retrieval pathway in either case brings back the original components. KDEL is an ER retrieval signal that is important for a protein to retain in the ER lumen.

Summary Introduction

To explain: If designing the system, the compartments in which KDEL receptor would concentrate.

Concept introduction: The retrieval pathway is a pathway that balances the flow of membrane between components. This work in opposite direction of secretory pathway and endocytic pathway bringing membrane proteins and some selected proteins back to its original component. The transports vesicles continually bud off from one membrane and fuse with another membrane. This carries forward the membrane components and soluble molecules. The secretory pathways work from endoplasmic reticulum (ER) to Golgi apparatus and to cell surface. The endocytic pathway works from plasma membrane to Golgi apparatus and to ER. The retrieval pathway in either case brings back the original components. KDEL is an ER retrieval signal that is important for a protein to retain in the ER lumen.

Summary Introduction

To predict: That the KDEL receptor which is a transmembrane protein would itself possess an ER retrieval signal.

Concept introduction: The retrieval pathway is a pathway that balances the flow of membrane between components. This work in opposite direction of secretory pathway and endocytic pathway bringing membrane proteins and some selected proteins back to its original component. The transports vesicles continually bud off from one membrane and fuse with another membrane. This carries forward the membrane components and soluble molecules. The secretory pathways work from endoplasmic reticulum (ER) to Golgi apparatus and to cell surface. The endocytic pathway works from plasma membrane to Golgi apparatus and to ER. The retrieval pathway in either case brings back the original components. KDEL is an ER retrieval signal that is important for a protein to retain in the ER lumen.