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UBA-like domain found in FAS-associated factor FAF1, FAF2 and similar proteins FAF1, also called UBX domain-containing protein 12 or UBX domain-containing protein 3A, is an apoptotic signaling molecule that acts downstream in the Fas signal transduction pathway. It interacts with the cytoplasmic domain of Fas, but not to a Fas mutant that is deficient in signal transduction. FAF1 is widely expressed in adult and embryonic tissues, and in tumor cell lines, and is localized not only in the cytoplasm where it interacts with Fas, but also in the nucleus. FAF1 contains phosphorylation sites for protein kinase CK2 within the nuclear targeting domain. Phosphorylation influences nuclear localization of FAF1 but does not affect its potentiation of Fas-induced apoptosis. Other functions have also been attributed to FAF1. It inhibits nuclear factor-kappaB (NF-kappaB) by interfering with the nuclear translocation of the p65 subunit. Although the precise role of FAF1 in the ubiquitination pathway remains unclear, FAF1 interacts with valosin-containing protein (VCP) which is involved in the ubiquitin-proteosome pathway. FAF2, also called protein ETEA, UBX domain-containing protein 3B, or UBX domain-containing protein 8, is the translation product of a highly expressed gene in the T-cells and eosinophils of atopic dermatitis patients compared with those of normal individuals. FAF2 shows homology to Fas-associated factor 1 (FAF1). Both of them contain N-terminal ubiquitin-associated (UBA)-like domain, UAS and ubiquitin-like (UBX) domains. Compared to FAF1, however, FAF2 lacks the nuclear targeting domain. The function of FAF2 remains unclear. A yeast two-hybrid assay showed that it can interact with Fas. Because of its homology to FAF1, it is postulated that FAF2 could be involved in modulating Fas-mediated apoptosis of T-cells and eosinophils of atopic dermatitis patients, making them more resistant to apoptosis. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",