第7章细胞质基质与内膜系统

A. Cytosol and its functions
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1. Cytosol (cytoplasmic matrix) concept
➢Cytosol: The region of fluid
content of the cytoplasm outside of the membranous organelles. Aqueous solution of large and small molecules including filaments of cytoskeleton which act as organizer for some order.
The Dynamic Nature of the Endomebrane 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.
• The synthesis site of some protein and fatty acid
• The cytoskeleton related functions:
– 维持细胞形态、细胞运动、胞内物质运输及能量传递； 细胞质基质结构体系的组织者
• The cytomembrane related functions:
➢The Cytosol is the site of protein synthesis and degradation or modification. It also performs most of the cell’s intermediary metabolism.
Macromolecular crowding
• Phosphorylation and phosphorylation
• Methylation
• Acylation.
Control for the life of protein
N 端第一个氨基酸残基是决定蛋白质寿命的信号:
Met/Ser/ Thr/ Ala/Val/Cys/Gly/Pro (stable)
B. Endomembrane system and functions
❖Endomembrane System : The structure, functions and so that biogenesis relationship organelles including ER, Golgi complex, lysosome, endosomes, secretory vesicles. They are found in all eukaryotic cells.
The crowded state of the cytoplasm in (a) eukaryotic and (b) E. coli cells
2. Functions of Cytosol
• Performs most of the cell’s intermediary metabolism. 如糖酵解、磷酸戊糖途径、糖醛酸途径等
第7章 细胞质基质与内膜系统 Cytosol and Endomembrane system
The Compartmentalization in Eukaryotic Cells
❖Membranes divide the cytoplasm of eukaryotic cells into distinct tree categories :
(1) the endomembrane system: ER, Golgi complex,Lys., secretory vesicles. (2). mitochondria, chloroplasts,
peroxisomes, and the nucleus. (3) the cytosol
Ubiquitin-and proteasome-mediated proteins degradation pathway
2004 :The Nobel Prize for chemistry
• 发现泛素调节的蛋白质降解
Degradation for degeneration and misfolded proteins
– 细胞质基质产生区室化；依 靠细胞膜或细胞器膜上的泵 蛋白和离子通道维持细胞内外跨膜的离子梯度
• The modification or selective degradation of proteins.
The modifications of proteins
• Covalent bonding between coenzyme /prosthetic group and enzymes.
细胞质基质中的变 性蛋白质、错误折 叠的蛋白质、 含有 被氧化或其他非正 常修饰氨基酸的蛋 白质，不管其 N 端 氨基酸残基是否稳 定，常常很快被降 解清除
Help degeneration and misfolded proteins to refold
热休克蛋白（heat shock protein， HSP）：一类进化上高度 保守的蛋 白质家族，作为分子伴 侣（molecular chaperone） 发挥多种作用，协助细胞内蛋白质合成、分选、折叠与装配等