Alternative splicing generates two isoforms of the beta(3)-adrenoceptor which are differentially expressed in mouse tissues

1 The beta(3)-adrenoceptor (AR) differs from the beta(1)-AR and beta(2)-ARs in having introns within and downstream of the coding block. This study de monstrates two splice variants of the mouse beta(3)-AR which differ within the coding region. 2 Reverse transcription/polymerase chain reaction with intron-spanning prim ers was used to demonstrate the splice variant of the mouse beta(3)-adrenoc eptor. The novel beta(3b)-AR has 17 amino acids encoded by exon 2 (SSLLREPR HLYTCLGYP) which differ from the 13 in the known beta(3a)-AR (RFDCYEGARPFPT ). 3 beta(3b)-AR mRNA is differentially expressed in mouse tissues, with level s relative to beta(3a)-AR mRNA highest in hypothalamus, cortex and white ad ipose tissue, and lower in ileum smooth muscle and brown adipose tissue.