Neuromuscular

Home, Search, Index, Links, Pathology, Molecules, Syndromes,
Muscle, NMJ, Nerve, Spinal, Ataxia, Antibody & Biopsy, Patient Info


MYOSIN AND ASSOCIATED MUSCLE PROTEINS

M-line
Muscle contraction
  Skeletal
  Smooth
Myosin
  Associated proteins
  Disorders
  Heavy chains
  Light chains
  Molecular regions
  Other: Non-muscle
  Structure
  External link: Myosin Homepage
Neuromuscular junction
  Presynaptic
  Postsynaptic
Smooth muscle
Thick filaments
  Myosin
  Non-myosin proteins
Thin filaments
  Actin
  Regulatory proteins
    Tropomyosin
    Troponin
  Structural components
Z-line
  Costameres

Dystrophin & related proteins
Muscle fiber structure & contraction
Skeletal muscle sarcomere

M Line Thick Filament Thick Filament Thick Filament Thick Filament Thin Filament Thin Filament Thin Filament Thin Filament Thin Filament Thin Filament Z-Line Z-Line Z-Line Muscle Fiber Structure
Click on structure for more information




THICK FILAMENTS




Myosin
Myosin Heavy Chain Types: Human Muscle Muscle fiber features: Other
Fiber
  Type
Myosin: Heavy
    Chain Types
Tissue Myonuclear
Domain Size
Cytochrome
Oxidase
NADH PAS &
Phosphorylase
Lipid ATPase
pH 4.3
ATPase
pH 4.6
ATPase
pH 9.4
I; Slow I (MYH7)
        (Cardiac β)
Skeletal muscle
  MYH7: 6 wks to Adult
Cardiac muscle
  Fetal
  Cardiomyopathy
Moderate High High Low High High High Moderate
IIa; Fast IIA (MYH2)
  ± I (MYH7)
Skeletal muscle
  MYH2: 24 wks to Adult
Larger Moderate Moderate High Moderate Absent
  or Low
Absent
  or Low
High
IIb; Fast IIA (MYH2)
  + IIX (MYH1)
  ± I (MYH7)
Skeletal muscle Largest Low Low Moderate Low Absent
  or Low
Moderate High
IIc I (MYH7)        
> IIA (MYH2)
Skeletal muscle
  Immature fibers
Smaller Low High Moderate High Moderate Moderate Moderate-
  High
Fetal IIB (MYH4) Skeletal muscle
  Regeneration, Early
  Not in adult
Small
Central
  core
I (MYH7)        
+ IIX (MYH1)
Skeletal muscle
  Most fibers
Moderate Moderate Moderate
Other Embryonic
        (MYH3)
Skeletal muscle
  Fetal, 6 to 24 wks
  Not adult
Other Neonatal
        (MYH8)

Skeletal muscle
  Fetal, 7 wks to Birth
  Regeneration
  Not normal adult
Super
  fast
MYH13
  (II eom)
Extraocular muscle
Tonic Slow tonic Extraocular, intrafusil,
  Tensor tympani
Cardiac,
  adult
Cardiac α
        (MYH6)
Cardiac atria
  Jaw muscle, Some
Moderate Moderate Moderate
Smooth Smooth muscle
    (MYH11)
Aorta, Intestine
Other Myosin 6
  (MYO6)
Muscle
Inner ear
Non-
  muscle
Type A
        (MYH9)
Fibroblast
Endothelial cell
Macrophage
Type B
        (MYH10)
Postsynaptic density
Myosin 7A
Myosin 14
Myosin 15
Ear
Myosin 5A
Skin
Immune cells
Also see
  Fiber type disorders
  Myosin disorders
External link: Myosin classes
Non-myosin components in thick filament
MyBPC1 labeled with GFP:
Localizes to C zones in A-band


From: C Weihl MD
M line Disorders of myosin 5


THIN FILAMENTS

Actin
Regulatory proteins
Structural components
Z-line

Actin Regulatory proteins of thin filament Thin filaments: Structural components & Associated structures

SKELETAL MUSCLE CONTRACTION & RELAXATION

Resting muscle Muscle contraction
  1. Sarcolemma depolarization: Spreads to internal T tubule system
  2. Cytosolic Ca++ Increased
  3. Myosin binding sites on actin become available
  4. Actin-myosin complex formed
  5. Binding influenced by phosphorylation of myosin light chain
  6. Dissociation of Pi and ADP
  7. Conversion of myosin to low-energy conformational state
  8. Rapid myosin conformational changes about its hinge points
  9. Translocation of attached thin filament toward the M line of sarcomere
Muscle relaxation
  1. Sarcoplasmic membrane & T tubule return to resting potential
  2. Sarcoplasmic Ca++ reduced
  3. Sarcoplasmic Ca++ also sequestered in mitochondrial matrix
  4. Original conformational states of troponin and tropomyosin recur
  5. Interaction between actin & myosin prevented
Muscle Fiber Contractile Types

SMOOTH MUSCLE

Structure & Function

OTHER (UNCONVENTIONAL) MYOSINS

Myosins: General properties Hearing loss with abnormal unconventional myosin heavy chains Other myosins & syndromes
Griscelli syndrome 2
  RAS-associated protein RAB27A (RAB27A) ; Chromosome 15q21.3
Return to Myopathies
Return to Neuromuscular home page

References
1. J Neuroimmunol 1999;98:130-135
2. Am J Hum Genet 2002;August
3. PNAS 2002;99:14801–14806
4. J Biol Chem 2003;Online Jan 29
5. Neuromuscul Disord 2007; Apr 12
6. Acta Neuropathol 2012; Online July

5/17/2014