I recently published a paper in Journal of Biological Chemistry and as part of the process, authors have the chance to send an image as a suggestion for the cover. The protein at the centre of my research was the lipid transfer protein, RdgBβ. The structure of RdgBβ itself has not been solved, and so I used MODELLER software to make my own model based on another member of the lipid transfer protein family, PITPβ. RdgBβ is the purple/grey protein in the illustration below, and is unique among its family as it has a long, extended tail. Such long, disordered regions are notoriously difficult to model, and so I added this part by hand. I hypothesised that when RdgBβ binds its partner, 14-3-3, through its tail, the tail becomes structured, and therefore I drew the tail as a zig-zag line when RdgBβ is bound to 14-3-3 (black).
The large RdgBβ in the foreground has dissociated from 14-3-3, enabling it to interact with the membrane and exchange its bound lipid. Its long tail is now completely unstructured. RdgBβ moves to the membrane when cells are stimulated, by associating with an integral membrane protein, ATRAP (three-pass transmembrane protein shown in the foreground in grey). The x-ray crystal structure of ATRAP has not been solved, neither have any closely-related proteins, and so I have drawn in ATRAP by hand. You’ll notice I have retained my hairpin motif to depict the membrane.
The molecular models were visualised using PyMOL software, and brought together with freehand drawing using Adobe Illustrator. My husband used his magic Photoshop skills to render and make the image into a more coherent illustration.
Unfortunately J Biol Chem chose to go with someone else’s image, which was disappointing.
Garner, K., Hunt, A.N., Koster, G., Somerharju, P., Groves, E., Li, M., Raghu, P., Holic, R., Cockcroft, S. (2012) Phosphatidylinositol Transfer Protein, Cytoplasmic 1 (PITPNC1) Binds and Transfers Phosphatidic Acid. J Biol Chem. 287(38):32263-76. PMID: 22822086.
Garner, K., Li, M., Ugwuanya, N., Cockcroft, S. (2011) The phosphatidylinositol transfer protein RdgBβ binds 14-3-3 via its unstructured C-terminus, whereas its lipid-binding domain interacts with the integral membrane protein ATRAP (angiotensin II type I receptor-associated protein). Biochem J. 439(1):97-111. PMID: 21728994.