Chapter 9 Cytoskeleton System 1. Introduction A Conception of Cytoskeleton(Narrow sense) A complex network of interconnected microfilaments, microtubules and intermediate filaments that extends throughout the cytosol Microtubules Microfilaments Intermediate filaments
Cytoskeleton System A. Conception of Cytoskeleton (Narrow sense) A complex network of interconnected microfilaments, microtubules and intermediate filaments that extends throughout the cytosol. Chapter 9 Microbubules Microfilamemts Intermediate filaments 1. Introduction
B Techniques for studying the cytoskeleton o Fluorescent microscopy and Electron microscopy: Immunofluorescence: fluorescently-labeled antibod Fluorescence: microinject into living cells Video microscopy: in vitro motility assays Electron: Triton X-100, Metal replica Quick freezing-deep etching EM Biochemical analysis (in vitro Difference centrifugation; SDS-PAGE 4 Drugs and mutations(about functions
B. Techniques for studying the cytoskeleton ❖ Fluorescent microscopy and Electron microscopy : Immunofluorescence: fluorescently-labeled antibody Fluorescence: microinject into living cells Video microscopy: in vitro motility assays Electron: Triton X-100, Metal replica Quick freezing-deep etching EM ❖ Biochemical analysis (in vitro) Difference centrifugation; SDS-PAGE ❖ Drugs and mutations (about functions)
C. The self-assembly and dynamic structure of cytoskeletal filaments Each type of cytoskeletal filament is constructed from smaller protein subunits. The cytoskeleton is a network of three filamentous structures o The cytoskeleton is a dynamic strucrure with many roles
C. The self-assembly and dynamic structure of cytoskeletal filaments ❖Each type of cytoskeletal filament is constructed from smaller protein subunits. ❖The cytoskeleton is a network of three filamentous structures. ❖The cytoskeleton is a dynamic strucrure with many roles
2. Microfilament MF A MFS are made of actin and involved in cell motility. Using ATP, g-actin polymerizes to form MF(F-actin) plus end actin molecule plus end COOH (ADP when in filament) minus end
2. Microfilament, MF A. MFs are made of actin and involved in cell motility. ❖Using ATP, G-actin polymerizes to form MF(F-actin)
B MF assembly and disassembly Characteristics: (I)Within a me, all the actin monomers are oriented in the same direction, so MF has a polarity Light chains Minus end Myosin ..ooooo.o Myosin is (a) Bret treatment with trypsin Hinge egion Heads Actn molecular motor for 。4+ Myosin segmen actins Tht meromyosin Heavy meromyosin (b)Further treatment with trypsin Subfragment 1 Subfragment 2 (s2) Plus end 025m Plus(barbed)end Subfragment 1 (c) EM and diagram of S1 fragments'decoratingactin microfilaments
B. MF assembly and disassembly ❖Characteristics: (1) Within a MF, all the actin monomers are oriented in the same direction, so MF has a polarity Myosin is molecular motor for actins