Translocation pathways

Dutzler, R., et al. Crystal structures of various mal-tooligosaccharides bound to maltoporin reveal a specific sugar translocation pathway. Structure 4 127-134, 1996. 

Angelini, S., Moreno, R., Gouffi, K. et al. (2001) Export of Thermus thermophilus alkaline phosphatase via the twin-arginine translocation pathway in Escherichia coli. FEBS Letters, 506 (2), 103-107. 

The hexose-6-phosphate transporter UhpT protein also contains 12 transmembrane (TM) regions. Based on experimental data, Hall and Maloney [113] conclude that TM11 spans the membrane as an a-helix with approximately two-thirds of its surface lining a substrate translocation pathway. It is suggested that this feature is a general property of carrier proteins in the Major Facilitator Superfamily, and that, for this reason, residues in TM11 will serve to carry determinants of substrate selectivity [113]. 

Brink, S., Bogsch, E., Edwards, W., Hynds, P., and Robinson, C. (1998). Targeting of thylakoid proteins by the ApH-driven twin-arginine translocation pathway requires a specific signal in the hydrophobic domain in conjunction with the two-arginine motif. FEBS Lett. 434, 425—430. 

Santini, C.-L., Ize, B. Chanal, A., Muller, M., Giordano, G., andWuL.-F., (1998). A novel sec-independent periplasmic protein translocation pathway in Escherichia coli. EMBO... 

Hsieh HL, Schafer BW, Cox JA, Heizmann CW. 2002. S100A13 and S100A6 exhibit distinct translocation pathways in endothelial cells. J Cell Sci 115(Pt 15) 3149—3158. 

Tanford, C. (1983). Translocation pathway in the catalysis of active transport. Proc. Natl. Acad. Sci. USA 80, 3701-3705. 

Oxidative phosphorylation occurs in the mitochondria of all animal and plant tissues, and is a coupled process between the oxidation of substrates and production of ATP. As the TCA cycle runs, hydrogen ions (or electrons) are carried by the two carrier molecules NAD or FAD to the electron transport pumps. Energy released by the electron transfer processes pumps the protons to the intermembrane region, where they accumulate in a high enough concentration to phosphorylate the ADP to ATP. The overall process is called oxidative phosphorylation. The cristae have the major coupling factors F, (a hydrophilic protein) and F0 (a hydrophobic lipoprotein complex). F, and F0 together comprise the ATPase (also called ATP synthase) complex activated by Mg2+. F0 forms a proton translocation pathway and Fj... 

Koehler, C. M. (2000). Protein translocation pathways of the mitochondrion. FEBS Lett. 476, 27-31. 

A second highly conserved buried carboxyl of Glu-14 is hydrogen bonded to the amide nitrogens of Leu-67 and His-66. Thus the carbonyls of His-66, Ala-65, and Gly-64 are strongly oriented in the cytoplasmic vestibule of the channel by interactions with the carboxyl of Glu-14. The oriented carbonyls are the quasi twofold equivalent of those at residues 199—201 in the external vestibule. This creates a path of hydrogen bond acceptors that make a line down one wall of the channel. While glycerol is resolved at three sites through the translocation pathway, there may be other partially occupied intermediate sites that are interpreted here as water molecules. 

Fig. 7.2. The structure of the translocation pathway in mycelial cords. (A) Hyphae fanning out at the distal end of a cord of Phanerochaete velutina (scanning electron microscopy by A. Yarwood) (B) Internal structure of a cord of Serpula lacrymans, showing vessels and cytoplasm-filled hyphae and extracellular matrix material. (C) Diagram of the components of the translocation pathway (adapted from Cairney, 1992) V, vessel hypha f, foraging front a, anastomosis (D) A cord system in beech woodland showing both corded mycelium and diffuse growth in contact with the wood substrate.

Figure 3 Ribbon diagram of cytochrome f from R laminosum (66). The heme cofactor is shown as sticks, and the five water molecules that form a chain are shown as spheres. Conserved protein residues cluster around the heme, the water molecules, and the C-terminal connection to the transmembrane helix to form a proton translocation pathway.

Carney, S.A., W. Heideman and R.E. Peterson. 2,3,7,8-Tetrachlorodibenzo-p-dioxin activation of the aryl hydrocarbon receptor/aryl hydrocarbon receptor nuclear translocator pathway causes developmental toxicity through a CYPlA-independent mechanism in zebrafish. Mol. Pharmacol 66 512-521, 2004. 

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