This gene has been found in all vertebrate genomes sequenced to date. However, this gene has undergone a change in function in placental mammals compared to other species. Specifically, in fish, avian, and amphibian species, this gene encodes plasma membrane-bound beta-subunits of Na,K-ATPase. In placental mammals, the encoded protein interacts with the nuclear transcriptional coregulator SKIP and may be involved in the regulation of TGF-beta signaling. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Mar 2010].