The F-box/WD repeat-containing protein 1A also known as pIkappaBalpha-E3 receptor subunit is a protein that in humans is encoded by the BTRC (beta-transducin repeat containing) gene. This gene encodes a member of the F-box protein family which is characterized by an approximately 40 amino acid motif, the F-box. The F-box proteins constitute one of the four subunits of ubiquitin protein ligase complex called SCFs (SKP1-cullin-F-box), which function in phosphorylation-dependent ubiquitination. The F-box proteins are divided into 3 classes: Fbws containing WD-40 domains, Fbls containing leucine-rich repeats, and Fbxs containing either different protein-protein interaction modules or no recognizable motifs. The protein encoded by this gene belongs to the Fbws class; in addition to an F-box, this protein contains multiple WD-40 repeats. This protein is homologous to Xenopus bTrCP1, yeast Met30, Neurospora Scon2 and Drosophila Slimb proteins. It interacts with HIV-1 Vpu and connects CD4 to the proteolytic machinery. It also associates specifically with phosphorylated IkappaBalpha and beta-catenin destruction motifs, probably functioning in multiple transcriptional programs by activating the NF-kappaB pathway and inhibiting the beta-catenin pathway. [provided by RefSeq].