Integrated genomics/proteomics of the Torpedo californica electric organ to assess concordance with the mammalian neuromuscular junction (NMJ) proteome and to identify novel proteins

Background Branchial mesoderm of Torpedo californica transdifferentiates into an electric organ (EO) capable of generating high voltage discharges to stun fish. The EO contains a dense cholinergic synapses and has served as a biochemical model for the membrane specialization of motor neurons, the NMJ. We studied the genome/proteome of the EO to gain insight into its composition and determine if there is concordance with skeletal muscle and the NMJ. Results Of 433 proteins identified, 297 mapped to Torpedo cDNA sequences. We identified 14 uncharacterized proteins in the EO that are known to play a role in AChR clustering or signal transduction. In addition, two human open reading frames, C1orf123 and C6orf130, showed high sequence similarity to EO proteins. Our profile lists proteins that are highly expressed in muscle or are muscle‐specific. Synaptic proteins were present in the EO proteome but absent in the skeletal muscle proteome. Conclusions Our integrated genomic/proteomic analysis supports research describing a muscle‐like profile of the EO. We show that it is a repository of NMJ proteins but we present limitations on its use. We identified several uncharacterized proteins that may become candidates for signaling proteins not previously characterized as components of the NMJ. Current studies localize these components within myofibers using recombinant proteins to identify those specific to the NMJ.