Fig. 4.

SAXS analysis determining the anti-parallel helical orientation of SYCE1 core. a A series of N-, C- and N- and C-terminal fusions of SYCE1 core (amino acids 25–179) were generated. In parallel configurations, individual fusions would demonstrate short inter-MBP distances, whilst anti-parallel configurations would demonstrate long inter-MBP distances. In both cases, the double-fusion would provide long and short inter-MBP distances. b SEC-MALS analysis of SYCE1 core fusions demonstrating dimer formation. MBP-SYCE1-MBP (black, left), MBP-SYCE1 (black, right), and SYCE1-MBP (grey, left) showed molecular weights of 189 kDa, 118 kDa, and 115 kDa, respectively (theoretical dimers—211 kDa, 126 kDa, and 118 kDa). The MBP monomer (43 kDa) is shown in grey (right). c SEC-SAXS P(r) distributions of SYCE1 core fusions demonstrating that SYCE1 is an anti-parallel molecule; MBP-SYCE1 (black, solid), SYCE1-MBP (black, narrow dashes), MBP-SYCE1-MBP (black, wide dashes), and free MBP (grey). Maximum dimensions (Dmax) are indicated and the positions of intra-MBP and both parallel and anti-parallel inter-MBP peaks are highlighted