Fig. 6

Secondary structure of the CASKIN2 SAM tandem by NMR and X-ray methods. Closed and open rectangles denote the five helices in each SAM domain. Triangles denote two surface exposed amino acids (G537, K540) whose substitution suppressed oligomerization. Black squares denote amino acids that could not be assigned in 950 MHz NMR spectra of a CASKIN2 G537D/K540E double mutant. Ub denotes a ubiquitin site observed from a global proteomics survey of CASKIN1 [36]. Δ620 identifies the site of a C-terminal truncation of the G537D/K540E double mutant to delimit the boundary of helix 5 in solution. In the sequence comparison with CASKIN2, black boxes denote sequence similarity. Two red boxes denote differences between CASKIN2 and CASKIN2 that are predicted to reduce hydrophobic and ionic contacts at, and in the vicinity of, the linker region