This is a family of proteins that are involved in rRNA processing [1]. In a localisation study they were found to localise to the nucleus and nucleolus [2]. The family also includes other metazoa members from plants to mammals where the protein has been named BR22 and is associated with TTF-1, thyroid transcription factor 1 [3]. In the lungs, the family binds TTF-1 to form a complex which influences the expression of the key lung surfactant protein-B (SP-B) and -C (SP-C), the small hydrophobic surfactant proteins that maintain surface tension in alveoli [4].

1: A panoramic view of yeast noncoding RNA processing. Peng WT, Robinson MD, Mnaimneh S, Krogan NJ, Cagney G, Morris Q, Davierwala AP, Grigull J, Yang X, Zhang W, Mitsakakis N, Ryan OW, Datta N, Jojic V, Pal C, Canadien V, Richards D, Beattie B, Wu LF, Altschuler SJ, Roweis S, Frey BJ, Emili A, Greenblatt JF, Cell 2003;113:919-933. PMID:12837249

2: Global analysis of protein localization in budding yeast. Huh WK, Falvo JV, Gerke LC, Carroll AS, Howson RW, Weissman JS, O'Shea EK; Nature 2003;425:686-691. PMID:14562095

3: BR22, a 26 kDa thyroid transcription factor-1 associated protein (TAP26), is expressed in human lung cells. Yang MC, Wang B, Weissler JC, Margraf LR, Yang YS; Eur Respir J. 2003;22:28-34. PMID:12882447

4: The TTF-1/TAP26 complex differentially modulates surfactant protein-B (SP-B) and -C (SP-C) promoters in lung cells. Yang MC, Guo Y, Liu CC, Weissler JC, Yang YS; Biochem Biophys Res Commun. 2006;344:484-490. PMID:16630564