ECT2 (Epithelial Cell Transforming Sequence 2) is a guanine nucleotide exchange factor (GEF) that catalyses the exchange of GDP for GTP. It is a cell cycle regulator that plays key roles in cytokinesis [1-4]. ECT2 contains triple copies of the BRCT domain (BRCT0, BRCT1 (Pfam:PF12738) and BRCT2 (Pfam:PF00533) at the N-terminal, separated from the C-terminal DH (Pfam:PF00621) and PH (Pfam:PF21242) domains by a linker of about 100 residues. This entry represents the first BRCT domain, BRCT0 [3]. The BRCT and DH-PH domains mediate intra-molecular interactions that restrains ETC2 activity during interphase.

1: Structure and function of the Rad9-binding region of the DNA-damage checkpoint adaptor TopBP1. Rappas M, Oliver AW, Pearl LH; Nucleic Acids Res. 2011;39:313-324. PMID:20724438

2: Crystal structure of the N-terminal region of human Topoisomerase IIbeta binding protein 1. Huo YG, Bai L, Xu M, Jiang T; Biochem Biophys Res Commun. 2010;401:401-405. PMID:20858457

3: Crystal structure of triple-BRCT-domain of ECT2 and insights into the binding characteristics to CYK-4. Zou Y, Shao Z, Peng J, Li F, Gong D, Wang C, Zuo X, Zhang Z, Wu J, Shi Y, Gong Q; FEBS Lett. 2014;588:2911-2920. PMID:25068414

4: BRCT domains of the DNA damage checkpoint proteins TOPBP1/Rad4 display distinct specificities for phosphopeptide ligands. Day M, Rappas M, Ptasinska K, Boos D, Oliver AW, Pearl LH; Elife. 2018; [Epub ahead of print] PMID:30295604