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TRANSMEMBRANE HELIX 10
YIFVATVPVIVAFIMLRAYFL
(amino acids 1014 thru 1034)
There is a positively charged R1030 in this helix which is highly conserved between species. When mutated to a negatively charged amino acid, it did not change the conduction properties significantly compared to wild type CFTR. (same is true for Arg347 in TM6). For information on pore, see helix1.
All known 3D structures of membrane proteins show a preference for tyrosines and tryptophanes at membrane surfaces. TM10 probably has a tyrosine near both ends of the membrane-surface.
It has been found by experiment that tyrosine- and tryptophan-containing peptides representing stretches from the transmembrane domains of different integral membrane proteins (like presenilin and CFTR), are able to prevent oxidative lysis in clonal and primary cells. This suggests that perhaps tyrosines and tryptophans are able to provide antioxidant functions inside lipid membranes and therefore are able to protect cells from oxidative stress. Eur J Biochem 2000 Sep;267(18):5687-92
There are 6 positively charged amino acid residues in the transmembrane helices of CFTR (K95 in M1, R134 in M2, R334 and K335 as well as R347 in M6, R1030 in M10) and they seem to be highly conserved between species.
If amino acids in transmembrane helices line up on the same side of the helix every 3.6 residues, then each amino acid is rotated 100 degrees away from the amino acid residues on either end of it.