A) S. pombe, S. cerevisiae, and H. sapiens Fcp1 family members aligned to H. sapiens Scp1. Amino acid positions numbered with domains color-coded: FCPH domains (blue), insertion domains (yellow), the linker helix between FCPH and BRCT domains (green), and BRCT domains (pink). Blue boxes indicate the TFIIF interaction helix position in ScFcp1 and HsFcp1. Question mark indicates that it is unknown whether SpFcp1 interacts with SpTFIIF. B) Orthogonal views of the Fcp1(140–580) structure as a ribbon with arrows for β-strands and wide-ribbons for helices. A transparent molecular surface envelops the Fcp1 structure. Domains colored as in (A). Helices in the yellow helical insertion domain are labeled (Fig. 2). N and C denote amino- and carboxy- termini. Asp170-BeF3 (stick representation) indicates the position of the Fcp1 active site. Arrows and distances denote the dimensions of the canyon.