Motor, sensory and autonomic nerve terminals containing NAP-22 immunoreactivity in the rat muscle

Brain Res. 2004 Mar 26;1002(1-2):142-50. doi: 10.1016/j.brainres.2004.01.007.


Neuron-enriched acidic protein having a molecular mass of 22 kDa, NAP-22, is a Ca(2+)-dependent calmodulin-binding protein and is phosphorylated with protein kinase C (PKC). This protein is localized to the biological membrane via myristoylation and found in the membrane fraction of the brain and in the synaptic vesicle fraction. Recent studies showed that NAP-22 is localized in the membrane raft domain in a cholesterol-dependent manner and suggest a role for NAP-22 in maturation and/or maintenance of nerve terminals by controlling cholesterol-dependent membrane dynamics. The present study revealed the immunohistochemical distribution of NAP-22 in the peripheral nerves in rat muscles. In all examined muscles, nerve terminals in the motor endplates showed NAP-22 immunoreactivity associated with the membranes of synaptic vesicles and nerve terminals. In the muscle spindles, annulospiral endings, which made spirals around the intrafusal muscles, showed intense NAP-22 immunoreactivity. Autonomic nerve fibers around the intramuscular blood vessels also showed the immunoreactivity for NAP-22. NAP-22 immunoreactivity in these peripheral nerves was observed from birth to adulthood (100 days after birth). Though growth-associated protein-43 (GAP-43) immunoreactivity in these nerves was observed from birth, this immunoreactivity decreased from 20 days after birth. These findings suggest that NAP-22 is distributed and regulates functions in the motor, sensory and autonomic nerve terminals in the peripheral nervous system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autonomic Pathways / chemistry*
  • Autonomic Pathways / growth & development
  • Calmodulin-Binding Proteins / analysis*
  • Cytoskeletal Proteins*
  • Female
  • Male
  • Motor Neurons / chemistry*
  • Motor Neurons / physiology
  • Muscle Spindles / chemistry*
  • Muscle Spindles / growth & development
  • Nerve Tissue Proteins / analysis*
  • Neurons, Afferent / chemistry*
  • Neurons, Afferent / physiology
  • Presynaptic Terminals / chemistry
  • Presynaptic Terminals / physiology
  • Rats
  • Rats, Sprague-Dawley


  • Calmodulin-Binding Proteins
  • Cytoskeletal Proteins
  • Nerve Tissue Proteins
  • Basp1 protein, rat