Figure 1.

Mutations in the Sbh1p trans-membrane domain. A, The structure of Methanococcus jannaschii SecYEG complex. Green, SecY, yellow, SecE and red SecG. B, a view at the interface of SecG-SecY in M. jannaschii. Amino acids with blue are to face SecY complex according to crystal structure of SecY in M. jannaschii. Pictures were generated using PyMol (v0.99rc6). C, Sequence comparison of M. jannaschii SecG and S. cerevisiae Sbh1p. Asterisks indicate identical amino acids. The predicted tm-domain is underlined. The numbering is based in Sbh1p sequence. D, a helical wheel diagram of the predicted trans-membrane domains of M. jannaschii SecG (top left), wt Sbh1p (top right) and a selection of eight mutants identified (Sbh1TM-1 to Sbh1TM-8). The green arch indicates the side of β-subunit that is facing the SecG and proposed to face Sec61p. MjSecG amino acids coloured blue face MjSecY (top left wheel). Mutated amino acids in Sbh1TM1-8 are highlighted with a circle and red color. Proline (P) marked with the black dot corresponds to P54 in ScSbh1p and P30 in MjSecG. From this point the wheel is read anti-clockwise.