1.A.36 The Intracellular Chloride Channel (ICC) Family
Mammals possess an intracellular (endoplasmic reticular, Golgi and nuclear membrane) protein which in humans is 551 aas long and exhibits 3 - 5 TMSs. Homologues have been identified in rodents and frogs (see 1.A.36.1.5), but not in C. elegans or D. melanogaster. The protein has been shown to exhibit anion-selective channel activity (Nagasawa et al., 2001). Although it was isolated using a yeast MID1 gene mutant (see TC # 1.A.16), it does not exhibit appreciable sequence similarity to the yeast Mid1 protein. Of the 4 putative TMSs, TMSs 1 and 4 are strongly hydrophobic while TMSs 2 and 3 are only weakly hydrophobic. None is strongly amphipathic when the angle is set at 100° as is appropriate for an α-helix.