Transforming Growth Factor Beta Regulator 1 (TbRG1)

Using the p19(Arf) isoform of mouse Cdkn2a as bait in a yeast 2-hybrid screen of a mouse embryonic fibroblast cDNA library, followed by RT-PCR of human pancreas cDNA, Tompkins et al. (2006) cloned mouse and human TBRG1, which they called NIAM. The deduced human protein contains 411 amino acids.Using in vitro and in vivo binding assays, including reciprocal immunoprecipitation assays, Tompkins et al. (2006) confirmed that NIAM bound p19(ARF), but not the p16(INK4A) isoform of CDKN2A. NIAM appeared to function downstream of p19(ARF) in G1-phase growth arrest in both p53 (TP53)-dependent and p53-independent signaling pathways. NIAM expression was induced in cells undergoing arrest in response to DNA damage and TGF-beta-1 (TGFB1) treatment, suggesting it may also participate in antiproliferative pathways.