Localization of neuronal calcium sensor-1 at the adult and developing rat neuromuscular junction

Neuronal calcium sensor (NCS-1; frequenin) is a calcium-binding protein involved in the regulation of neurotransmission in the central and peripheral nervous systems from insects to vertebrates. This study reports the localization of NCS-1 immunoreactivity, by Western blotting and immunohistochemistry, at the adult and developing postnatal rat neuromuscular junction. Our confocal immunofluorescence results on the whole-mount muscle and on semithin cross-sections are indicative of the localization of NCS-1 to motor axon terminals. There is no evidence of immunoreactivity in the postsynaptic side of the neuromuscular junctions or teloglial Schwann cells. These results suggest that NCS-1 is involved in the formation and function of presynaptic nerve terminal part of the neuromuscular junction during synaptogenesis and in adult mammals.