Identification of a splice variant of mouse caveolin-2 mRNA encoding an isoform lacking the C-terminal domain

We identified a splice variant of mouse caveolin-2 mRNA having an intronic sequence in place of the third exon (Δex3). The entire sequence of full-length (FL) and Δex3 caveolin-2 mRNA was determined; their sizes were 2490 and 973 bp, respectively. The Δex3 mRNA encoded a putative isoform lacking the C-terminal 49 amino acids of the authentic caveolin-2. The expression level of Δex3 was lower than that of FL mRNA, but considerable in some culture cells and tissues. The isoform lacking the C-terminus localized to the endoplasmic reticulum, while the authentic caveolin-2 was distributed to the Golgi and the plasma membrane along with caveolin-1. The result confirmed the necessity of the C-terminal domain of caveolin-2 for the caveolar localization, and showed the existence of a novel caveolin-2 isoform, which is not recruited to caveolae even in the presence of caveolin-1.