考研资料：北京大学细胞生物学第六章基质与内膜(上).ppt

考研资料：北京大学细胞生物学第六章基质与内膜(上)
1. The Compartmentalization in Eukaryotic Cells
Membranes divide the cytoplasm of eukaryot 1
Lysosomes 1
Endosomes 1
Relative volumes occupied by the major intracellular compartments in Liver Cell
C. The Dynamic Nature of the Endomembrane System
Most organelles are part of a dynamic system in which vesicles move between compartments.
Biosynthetic parthways move proteins, carbohydrates and lipids within the cell.
Secretory pathways discharge proteins from cells.
Endocytic parthways move materials into cells.
Sorting signals are recognized by receptors and target proteins to specific sites.
D. A few approaches to the study of cytomembranes
Insights gained from autoradiography;
Insights gained from the biochemical analysis of subcellular fractions;
Insights gained from the study of genetic mutants;
The dynamic activities of endomembrane systems are highly conserved despite the structural diversity of different cell types.
Quality control of of newly synthesized proteins---The role of N-linked glycosylation in ER protein folding
Quality control: ensuring that misfolded proteins do not leave ER
The lumen of rER contains:
Bip and calnexin (chaperones) : that recognize and bind to unfolded or misfolded proteins and give them correct conformation;
Protein disulfide isomerase ( PDI ) ;
GT(glucosyl-transferase, monitoring enenzyme ) recognize unfolded or misfolded proteins and adds a glucose to the end of oligo..
Synthesis of membrane lipids
Most membrane lipids are synthesized enterly within the ER.
There are two exceptions:
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