 Traditional G protein-coupled receptor signaling proceeds primarily through Gsα-long and Gsα-short, the most abundant, ubiquitously-expressed protein products of this gene.XLαs is the "extra large" isoform, and has a very long N-terminal region with some internal repeats not well-conserved across species.The XL exon also encodes in another reading frame the protein product ALEX, an inhibitory cofactor binding to the unique domain.