| 2. |
- Lindblom, Anders, et al.
(författare)
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The intrinsic factor-vitamin B12 receptor, cubilin, is assembled into trimers via a coiled-coil alpha-helix
- 1999
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 274:10, s. 6374-6380
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Tidskriftsartikel (refereegranskat)abstract
- A large protein was purified from bovine kidney, using selective extraction with EDTA to solubilize proteins anchored by divalent cation-dependent interactions. An antiserum raised against the purified protein labeled the apical cell surface of the epithelial cells in proximal tubules and the luminal surface of small intestine. Ten peptide sequences, derived from the protein, all matched the recently published sequences for rat (Moestrup, S. K., Kozyraki, R., Kristiansen, M., Kaysen, J. H., Holm Rasmussen, H., Brault, D., Pontillon, F., Goda, F. O., Christensen, E. I., Hammond, T. G., and Verroust, P. J. (1998) J. Biol. Chem. 273, 5235-5242) and human cubilin, a receptor for intrinsic factor-vitamin B12 complexes, identifying the protein as bovine cubilin. In electron microscopy, a three-armed structure was seen, indicating an oligomerization of three identical subunits. This model was supported by the Mr values of about 1,500,000 for the intact protein and 440,000 for its subunits obtained by analytical ultracentrifugation. In a search for a potential assembly domain, we identified a region of heptad repeats in the N-terminal part of the cubilin sequence. Computer-assisted analysis supported the presence of a coiled-coil alpha-helix between amino acids 103 and 132 of the human cubilin sequence and predicted the formation of a triple coiled-coil. We therefore conclude that cubilin forms a noncovalent trimer of identical subunits connected by an N-terminal coiled-coil alpha-helix.
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| 4. |
- Tarnow, Peter, 1963, et al.
(författare)
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Topical D-myo-inositol-1,2,6-trisphosphate and hexylbetaine treatment reduces albumin extravasation in experimental rat skin burn injury.
- 1998
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Ingår i: Burns : journal of the International Society for Burn Injuries. - 0305-4179. ; 24:5, s. 460-3
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Tidskriftsartikel (refereegranskat)abstract
- The anti-inflammatory agent D-myo-inositol-1,2,6-trisphosphate (1,2,6-IP3) has shown beneficial effects in experimental burns following systemic administration. The purpose of this study was to investigate the effect of topical 1,2,6-IP3 cream on a standardised full-thickness 1 cm2 burn injury in rats. The experimental cream contained a transcutaneous absorption enhancer, hexylbetaine. Five different treatment groups were used. Two experimental groups of burned rats received either 1,2,6-IP3 cream with hexylbetaine (n = 10) or without hexylbetaine (n = 10). Two burned control groups were treated either with hexylbetaine cream (n = 10) or placebo cream (n = 10), while a third control group was untreated (n = 14). The various creams (0.5 g) were administered to the experimental burn area and allowed to remain for 3 h covered with an occlusive dressing. Spectrophotometrical quantification of Evans blue albumin extravasation was used to evaluate the effect of the experimental creams on vascular permeability following the burn trauma. Results showed a significant reduction of albumin extravasation both by 1,2,6-IP3 (p<0.05) and by hexylbetaine alone (p<0.01), as compared to placebo cream-treated animals. The transcutaneous absorption enhancer hexylbetaine did not further improve the effect of 1,2,6-IP3 on burn oedema. In conclusion, both topical 1,2,6-IP3 and hexylbetaine induced a significant reduction of albumin extravasation in burned skin. The effect of 1,2,6-IP3 could be related to previously shown anti-inflammatory actions of the agent, while the mechanisms of actions of hexylbetaine remain to be investigated.
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