Identification and classification of innexin gene transcripts in the central nervous system of the terrestrial slug Limax valentianus

In invertebrates, innexin is involved in the formation of single-cell membrane channels and intercellular gap junction channels. Generally, there are multiple isoforms of innexin family proteins in various animal species, which enable the precise regulation of channel function. In molluscan species, the sequence information of innexins is still limited and the sequences have not been classified. This study examined the innexin transcripts expressed in the central nervous system of the terrestrial slug Limax valentianus and identified 16 transcripts of 12 innexin isoforms, including the splicing variants. To examine the function of molluscan innexin isoforms, phylogenetic analysis was performed using the innexin sequences of molluscan species. Next, the phosphorylation, N-glycosylation, and S-nitrosylation sites in the isoforms were predicted to characterize the innexin isoforms. Further, 16 circular RNA sequences of nine innexin isoforms were identified in the central nervous system of Limax. The identification and classification of the gene transcripts of molluscan innexins provided novel insights for understanding the regulatory mechanism of innexins in the central nervous system.