Ryanodine receptors (RyRs) are a family of intracellular calcium release channels. Three cDNAs encoding different isoforms of RyR have been identified and cloned. We report the complete sequence of the mink RyR3 cDNA and the characterization of three alternative spliced regions. The first two splicing sites are represented by insertions of five and six amino acids, respectively. The third site is represented by a mutually exclusive splicing. The tissue distribution of the alternatively spliced transcripts revealed a ubiquitous expression of splicing site I and a differential distribution of sites II and III, indicating that a further level of complexity in RyR3 expression may result from alternative splicings in this gene.