Differential expression of alternative splice variants of β-arrestin-1 and -2 in rat central nervous system and peripheral tissues

Members of arrestin/β-arrestin protein family are thought to participate in agonist-mediated desensitization of G-protein-coupled receptors, including rhodopsin and β₂-adrenergic receptor. Unlike in human and cow, splice variants of this protein family in rat have not been studied extensively, and there has been no report on their existence at protein level. Hence, a previous report by others on the localization of both β-arrestin-1 and -2 in a wide range of innervated rat tissues could imply their broad receptor specificity. In this report we show the presence of two alternatively spliced forms of β-arrestin-1 in several rat tissues using both reverse transcription-polymerase chain reaction and Western immunoblot. Splicing of β-arrestin-1 pre-mRNA appears to be subject to differential regulation between the rat CNS and peripheral tissues. In contrast, we detected no splice variants of β-arrestin-2 in rat. A comparison of the genomic DNA sequences of bovine and rat β-arrestin-2, where the splicing of bovine β-arrestin-2 mRNA has been reported, revealed a high degree of homology in their organization of exons and introns as well as certain differences that might be responsible for the different processing of β-arrestin-2 mRNA in the two species. Our two-dimensional isoelectric focusing gels using rat spinal cord and heart tissues demonstrate isoelectric heterogeneity of rat β-arrestin-1, suggesting that β-arrestin-1 is subject to post-translational modification unlike β-arrestin-2.