Nuclear Receptor Binding Protein 1 (NRBP1)

The deduced 535-amino acid human protein has a molecular mass of 59.8 kD and contains 2 putative nuclear receptor-binding motifs, a putative binding domain for SH2 domain-containing proteins, a kinase-like domain, a bipartite nuclear localization signal, and 3 sequences rich in glutamic acid, serine, proline, and threonine (PEST) residues. Northern blot analysis detected ubiquitous expression of a 2.4-kb NRBP transcript, with highest levels in testis and lowest levels in thymus. Dot-blot analysis showed highest levels in testis and placenta and lowest levels in hippocampus and thymus. NRBP mRNA was also expressed in each of 15 cultured human tumor cell lines examined. Translation of NRBP mRNA in vitro revealed 3 translation products of 60, 51, and 43 kD, suggesting that translation of NRBP may initiate at multiple sites.