May inhibit the adenylyl cyclase-stimulating activity of guanine nucleotide-binding protein G(s) subunit alpha which is produced from the same locus in a different open reading frame. Interacts with the N-terminal region of the XLas isoforms of guanine nucleotide-binding protein G(s) subunit alpha. Predominantly associated with cell membrane ruffles. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Most affected individuals have defects in methylation of the gene. In some cases microdeletions involving the STX16 appear to cause loss of methylation at exon A/B of GNAS, resulting in PHP1B. Paternal uniparental isodisomy have also been observed. The disease may be caused by variants affecting the gene represented in this entry. This protein is produced by a bicistronic gene which also produces guanine nucleotide-binding protein G(s) subunit alpha from an overlapping reading frame. Belongs to the ALEX family.