Wikinotes

Maintainer: admin

myelin makes action potential go faster
- saltatory conduction: jumping of action potential from one booster station to the next, 10 times faster than unmyelinated axon
- Node of Ranvier : Gaps between sections of myelination, booster stations
Schwann cells myelinate one single axon
Oligodendrocyte can myelinate 50+ axons

Major dense line: between layers of myelin, extracellular
intraperiod lines: appear like a line, cytosol of myelin, intracellular

70-85% lipids and 13-30% protein
no lipid specific to myelin
- important to maintain formation of myelin sheath
major proteins
- MBP (myelin basic protein) - in CNS and PNS
  - on cytoplasmic face of membrane
  - stabilizes major dense line
  - EAE: autoimmune disease against it
  - shiverer : MBP mutant mouse, shiver a lot.
    - lack of dense lin in CNS,
    - PNS isn't too affected (probably due to Po)
- PLP (Proteolipid protein) - specific to CNS myelin
  - Transmembrane protein
  - stabilizes intraperiod line of CNS
  - jimpy : PLP mutant mice, tremors and seizures
- Po (protein zero): specific to PNS
  - immunoglobulin superfamily of cell adhesion molecule
  - promotes formation of intraperiod line (homophilic binding to the adjacent layer)
  - and major dense line (via positively charged cytoplasmic domain)
  - function similar to BMP
minor protein
- MAG (myelin associated glycoprotein)
  - member of Ig superfamily of cell adhesion molecule
  - KO mice: degenerative alterations of PNS myelin
  - mediator of the axon glial adhesion that precedes myelination
  - direct initial tucking under the myelin rings
- P2
  - stability of the major dense line
- CNP
- OMgp

glial cell adhesion molecules are recruited to the point of contact between neurons and glia
ankyrin G retamins and stabilizes ion channels at notes of Ranvier
paranode and justaparanode act as molecular block and mkae sodium channels and other proteins stay between the noes

CNS don't regenerate well because their environment is inhibitory
- removal of debris is also slow and myelin membrane produce molecules that inhibit growth
PNS is faster. faster macrophage clearance

acquired diseases (i.e. multiple sclerosis)
hereditary nerodegenerative disorders (i.e. leukodystrophies)