Integrated genomics and proteomics of the Torpedo californica electric organ: concordance with the mammalian neuromuscular junction

Of 435 proteins identified, 300 mapped to Torpedo cDNA sequences with ≥2 peptides. We identified 14 uncharacterized proteins in the electric organ that are known to play a role in acetylcholine receptor clustering or signal transduction. In addition, two human open reading frames, C1orf123 and C6orf130, showed high sequence similarity to electric organ proteins. Our profile lists several proteins that are highly expressed in skeletal muscle or are muscle specific. Synaptic proteins such as acetylcholinesterase, acetylcholine receptor subunits, and rapsyn were present in the electric organ proteome but absent in the skeletal muscle proteome.Our integrated genomic and proteomic analysis supports research describing a muscle-like profile of the organ. We show that it is a repository of NMJ proteins but we present limitations on its use as a comprehensive model of the NMJ. Finally, we identified several proteins that may become candidates for signaling proteins not previously characterized as components of the NMJ.Ionic gradients across cell membranes (bioelectricity) are utilized by all organisms. Some fish have developed extreme adaptations of bioelectricity with the evolution of electric organ systems. It is thought that electric organs have evolved independently six or seven times in fish and can be classified as either weak or strong, which is reflective of the size and function of the organs within the fish. For example, Gymnotids are weakly electrogenic and only possess accessory electric organs used for electroreception and electrolocation [1]. In contrast, Torpedinid and Electrophorous are strongly electrogenic and possess organs that account for approximately one-third of the organism's mass and are used for generation of electric shocks for predation or protection [2].Developmental studies have shown most electric organs are derived from muscle anlage tissue; the exception is the neurogenic development of the Sternarcus electric organ. Several basic differenc