Hi Michael, Thanks for the information.
It is amphipathic. It follows a transmembrane helical domain of a cell surface receptor and adopts an orientation parallel to the membrane. So it may be associated with the membrane. I am just wondering if such leucine-repeat motif is special among all amphipathic, membrane-associated helical structures. In other words, any other possible functional roles than just membrane association? Best, Cheng On Sat, Mar 3, 2018 at 10:23 PM, R. Michael Garavito <rmgarav...@gmail.com> wrote: > Dear Cheng, > > Chris and Ruud have provided you with the typical interpretation of such a > motif, but you have forgotten to give the CCP4 community the context of > this leucine-repeat helix. Is it amphipathic? Does the protein also have > transmembrane helices (as suggested by the figure provided) which would > provide the membrane anchoring? > > Look up structurally similar membrane proteins (not necessarily homologous > by sequence), such as proteins which have a monotonic-like membrane > interaction, but that also have a transmembrane helix (monoamine oxidase or > some mammalian cyt P450s). If your protein is monotopic, look at that > class of membrane proteins (squalene cyclase, fatty acid hydrolase, > cyclooxygenase, etc.). One structurally undescribed motif is a “reentrant > membrane helix.” In other words, look at context before assigning > function. > > Good luck and hope this helps, > > Michael > > ****************************************************************** > > *R. Michael Garavito, Ph.D.* > > *Professor of Biochemistry & Molecular Biology* > > *513 Biochemistry Bldg. * > > *Michigan State University * > > *East Lansing, MI 48824-1319* > > *Office:* *(517) 355-9724 <(517)%20355-9724> Lab: (517) 353-9125 > <(517)%20353-9125>* > > *FAX: (517) 353-9334 <(517)%20353-9334> Email: > rmgarav...@gmail.com <garav...@gmail.com>* > > ****************************************************************** > > > > On Mar 3, 2018, at 3:51 PM, Cheng Zhang <chengzh1...@gmail.com > <chengzh1...@gmail.com>> wrote: > > Hi all, > > We recently got a structure of a transmembrane protein. There is a helix > that is parallel to the membrane. The function of this helix is not known > and we are trying to make some hypothesis. A unique feature is that there > are repeated leucine residues on this helix facing the lipids. I am > wondering if anyone has seen a similar pattern and could suggest possible > function, e.g. membrane anchoring? > > Thanks! > > Best, > > Cheng > > <LeuRHelix.jpg> > > > -- > --------------------- > Cheng Zhang > > > -- --------------------- Cheng Zhang
