Guanine nucleotide-binding proteins (G proteins) function as transducers in numerous signaling pathways controlled by G protein-coupled receptors (GPCRs). Signaling involves the activation of adenylyl cyclases, resulting in increased levels of the signaling molecule cAMP. GNAS functions downstream of several GPCRs, including beta-adrenergic receptors. XLas isoforms interact with the same set of receptors as GNAS isoforms (By similarity). G proteins are composed of 3 units; alpha, beta and gamma. The alpha chain contains the guanine nucleotide binding site. Interacts through its N-terminal region with ALEX which is produced from the same locus in a different open reading frame. This interaction may inhibit its adenylyl cyclase-stimulating activity (By similarity). Interacts with MAGED2 (PubMed:27120771). 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 is caused by variants affecting the gene represented in this entry. This protein is produced by a bicistronic gene which also produces the ALEX protein from an overlapping reading frame. The GNAS locus is imprinted in a complex manner, giving rise to distinct paternally, maternally and biallelically expressed proteins. The XLas isoforms are paternally derived, the Gnas isoforms are biallelically derived and the Nesp55 isoforms are maternally derived. Belongs to the G-alpha family. G(s) subfamily.