BIOCHEMISTRY OF MUSCLE CONTRACTION

 

This home page contains selected graduate course lectures
PHYB-BCHE 516,
given between
1975-1997,
by Michael and Kate Bárány,

University of Illinois at Chicago


Updated: August 2006


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CONTENTS

INTRODUCTION

SKELETAL MUSCLE

Disintegration of the Muscle

Contractile Proteins

Myosin

Structure                  

Size and shape of the myosin molecule

Myosin light chains

Function

Myosin-actin binding

ATPase activity of myosin

Separate actin-binding and ATPase sites of myosin

Intermediates of the ATP hydrolysis

ATPase activity of myosin and speed of muscle shortening

Myosin heavy chains

Three-Dimensional Structure of Subfragment 1

                                                Structure-function relationship in myosin

                                                ATP hydrolysis catalyzed by myosin

                                                The converter domain of the myosin head 

                 Assembly

Myosin filament

Muscle fibers, myofibrils

Localization of myosin in the structure of muscle

                                    References

Actin

The two forms of actin

Actin-myosin binding

Three-Dimensional Structure of Actin

                                        Recent studies on the structure of actin

The intersubunit contacts in the F-actin filaments

Localization of actin in the structure of muscle

Structure of the thin filament

Mini-thin filaments

                                    References

Actin-Myosin Interaction

Structural model

Contact sites

            Lever Arm Model

Dynamics of actin-myosin interaction

X-ray Diffraction and Electron Microscopy of Muscle

In Vitro Motility Assay

                              References

Regulatory Proteins

Tropomyosin

Tropomyosin isoforms

Structure of tropomyosin

Binding properties

Troponin

Troponin C

Troponin I

Troponin T

            Recent X-ray Studies on Troponin Crystals

                                    References

Regulation of Skeletal Muscle Contraction

The Role of Ca2+ in Regulation of Skeletal Muscle Contraction

Historical experiments

The experiments of Huxley and Taylor

Current concepts

Sarcoplasmic Reticulum

Signal transduction between T-tubule and SR-junction

Ca2+-sparks

Excitation-Contraction Coupling

Sequence of events

References

Mechanism of Skeletal Muscle Contraction

The sliding filament theory

Length-tension relationship

Crossbridge cycle and its relation to actomyosin ATPase

X-ray Diffraction Studies of Muscle and the Crossbridge Cycle

References

Energetics

Historical Development of Muscle Energetics

The lactic acid theory and its disproof

The Lohmann reaction and its inhibition

ATP, Phosphocreatine and Glycogen Provide Energy for Muscle Contraction

Heat Production during Muscle Contraction

The relationship between energy output and chemical breakdown

Energy Cost Assessment in Humans

Direct calorimetry

Indirect calorimetry

Relationship between work-output and O2 consumption

Oxygen debt

Adaptation to exercise

Fatigue

References

 

HEART MUSCLE

                                                            Basic Physiology

                                                            Ultrastructure

Contractile Proteins

                                                            Myosin

                                                            Actin: Purification

Exchange of the actin-bound nucleotide in perfused rat heart

Regulatory Proteins

                                                            TN-C

                                                            TN-I

                                                            TN-T

                                                            The troponin complex

Structural model for phosphorylation sites in cardiac troponin                                                         

Structural and functional differences between cardiac and skeletal isoforms of troponin

TM

Movement of tropomyosin during the heart cycle

Methods

Displacement of endogenous TN in skinned fibers with TN mutants

Purification of cardiac myofibrils

Gel electrophoresis of the regulatory proteins

Regulation of Ca2+ Flow

Sarcoplasmic Reticulum

                                                            Ca2+induced Ca2+ release

                                                            Calsequestrin

                                                            Phospholamban

                                                            Factors controlling the Ca2+release from Sarcolemma

Ca2+sensitivity

Excitation-Contraction Coupling

                                                  Major events in cardiac E-C coupling

Biochemistry of Starling’s Law

Energetics

          Summary

References

SMOOTH MUSCLE

Structure

Innervation and stimulation

Myofibril proteins

Other proteins: Calveolins

                            CHASM

                            Twitchin

                            Sarcoplasmic reticulum

Phosphorylation and Dephosphorylation of the 20-kDa Myosin Light Chain

Myosin light chain kinase and myosin light chain phosphatase

Protein kinase for myosin light chain (LC)

Protein phosphatase for myosin LC

Regulation of Ca2+-sensitivity by KCl

“Dick Murphy three decades as the touchstone of smooth muscle physiology”

Myosin light chain phosphorylation followed by 32P-labeling in intact smooth muscle

Isoforms of the 20-kDa myosin light chain

Phosphorylation site

                                                            Two-dimensional tryptic peptide mapping

Need for Ca2+ and calmodulin for light chain phosphorylation in intact smooth muscle

Stretch-induced light chain phosphorylation

Phosphorylation of Heat Shock Proteins

Signal Transduction

Inositol 1,4,5-trisphosphate

Inositol 1,4,5-trisphosphate receptor

G-proteins

Phosphoinoside-specific phospholipase C

The Contractile Event of Smooth Muscle

Mechanism of Smooth Muscle Contraction

Activation of the Arp2/3 Complex  by N-WASP during Smooth Muscle Contraction

Monomer (G) to Polymer (F) Transformation of Actin in Smooth Muscle

Characteristics of the exchange of the actin-bound nucleotide in smooth muscle

                          References

CELL MOTILITY

                                                  Historical development of cell motility

Actin-Binding Proteins

Profilin

                              Gelsolin

                                                Structure and function

ADF/cofilin

Arp2/3 complex and WASp/Scar proteins

Dendritic nucleation model

Role of WASp homology domain 2 in actin filament      nucleation

                              Structural basis of actin filament nucleation

Actin in the cytoskeleton

Non-Muscle Myosins

                              Myosin V

                              Myosin VI

Microtubules

Kinesin and dynein

References

NUCLEAR MAGNETIC RESONANCE

           

Introduction

                                                            Basis of NMR

Machines and Accessories

History

Superconducting NMR spectrometer

Horizontal bore superconducting NMR spectrometer

One meter horizontal bore magnets

31P-Spectroscopy

Characteristic Parameters of  31P-NMR spectra

Chemical shift and Referencing

Intracellular pH

Identification of resonances

Coupling constants

Line width

 31P Spectral Profiles of Intact Muscles

Changes in 31P Spectra of Stimulated Muscles

The Central Role of PCr in Analyzing 31P Spectra

Changes in the human 31P spectrum during muscular exercise

Kinetics of PCr breakdown

Myosin ATPase activity

31P Spectroscopy of Heart Muscle

31P Spectroscopy of Smooth Muscle

31P Spectroscopy of Normal and Diseased Human Muscle

1H Spectroscopy

Assignment of 1H resonances

                                                Volume localized 1H spectroscopy

                                                Water suppressed 1H spectroscopy

                                                1H  spectroscopy  in the 21st century

13C Spectroscopy

                                                            Assignment of 13C resonances

Comparative spectra of normal and diseased muscle                    

Changes in the natural abundance 13C NMR spectra of intact frog muscle

                                      13C spectroscopy with 13C-labeled substrates

References

Recommended Readings

 

______________________________________________________________

For more information please contact

Michael Bárány

Department of Biochemistry and Molecular Genetics (M/C 536)

University of Illinois at Chicago

Chicago, IL 60612

e-mail: mbarany@uic.edu