Figure 1. Transmembrane architecture of a PIP synthase from R. salmoninarum.

(a) PIP synthases catalyse the transfer of a diacylglycerol-substituted phosphate group (purple/red) from the CDP-DAG donor to the inositol phosphate acceptor (green), generating PIP and CMP. (b) Structure of the RsPIPS-Δ6N homodimer in ribbon representation viewed from two orthogonal orientations (in the plane of the membrane on the left; towards the cytosol down the dimer axis on the right). One protomer is coloured grey, and the helices of the other are depicted in spectral colouring, from blue (JM1) to red (TM6). The Af2299 extramembrane domain used to facilitate crystallization is not shown here.