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PDBsum entry 1exs
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Lipid binding protein
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PDB id
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1exs
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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A novel ph-Dependent dimerization motif in beta-Lactoglobulin from pig (sus scrofa).
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Authors
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F.J.Hoedemaeker,
R.W.Visschers,
A.C.Alting,
K.G.De kruif,
M.E.Kuil,
J.P.Abrahams.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 2002,
58,
480-486.
[DOI no: ]
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PubMed id
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Abstract
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beta-Lactoglobulin (BLG) is a lipocalin and is the major protein in the whey of
the milk of cows and other ruminants, but not in all mammalian species. The
biological function of BLG is not clear, but a potential role in carrying fatty
acids through the digestive tract has been proposed. The capability of BLG to
aggregate and form gels is often used to thicken foodstuffs. The structure of
the porcine form is sufficiently different from other known BLG structures that
SIRAS phases had to be measured in order to solve the crystal structure to 2.4 A
resolution. The r.m.s. deviation of C(alpha) atoms is 2.8 A between porcine and
bovine BLG. Nevertheless, the typical lipocalin fold is conserved. Compared with
bovine BLG, the tilted alpha-helix alters the arrangement of surface residues of
the porcine form, completely changing the dimerization behaviour. Through a
unique pH-dependent domain-swapping mechanism involving the first ten residues,
a novel dimer interface is formed at the N-terminus of porcine BLG. The
existence of this novel dimer at low pH is supported by gel-filtration
experiments. These results provide a rationale for the difference in
physicochemical behaviour between bovine and porcine BLG and point the way
towards engineering such dimerization motifs into other members of the lipocalin
family.
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Figure 3.
Figure 3 (Divergent) stereo image of the dimer interface.
Residues forming side-chain interactions, as well as residues 1
and 13, are labelled. This figure was produced with SETOR
(Evans, 1993[Evans, S. V. (1993). J. Mol. Graph. 11,
134-138.]) [199][Figure 4]
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Figure 4.
Figure 4 Different (putative) dimeric forms of lipocalins.
Disulfide bridges are indicated in yellow; free cysteines are
indicated in green. The dimers were automatically generated from
the original PDB entries by the PQS server
([201]http://pqs.ebi.ac.uk ). (a) Bovine odorant-binding protein
([202]1obp ; Tegoni et al., 1996[203] [Tegoni, M., Ramoni, R.,
Bignetti, E., Spinelli, S. & Cambillau, C. (1996). Nature
Struct. Biol. 3, 863-867.]-[204][bluearr.gif] ), buried surface
area 2399.7 Å2. (b) Porcine BLG ([205]1exs ; this paper),
buried surface area 1757.7 Å2. (c) Major horse allergen (1ew3;
Lascombe et al., 2000[206] [Lascombe, M. B., Gregoire, C.,
Poncet, P., Tavares, G. A., Rosinski-Chupin, I., Rabillon, J.,
Goubran-Botros, H., Mazie, J. C., David, B. & Alzari, P. M.
(2000). J. Biol. Chem. 275, 21572-21577.]-[207][bluearr.gif] ),
buried surface area 1023.3 Å2. (d) Porcine odorant-binding
protein ([208]1e06 ; Spinelli et al., 1998[209] [Spinelli, S.,
Ramoni, R., Grolli, S., Bonicel, J., Cambillau, C. & Tegoni, M.
(1998). Biochemistry, 37, 7913-7918.]-[210][bluearr.gif] ),
buried surface area 848.2 Å2. (e) Nitrophorin 4 ([211]1eqd ;
Weichsel et al., 2000[212] [Weichsel, A., Andersen, J. F.,
Roberts, S. A. & Montfort, W. R. (2000). Nature Struct. Biol. 7,
551-554.]-[213][bluearr.gif] ), buried surface area 789.1 Å2.
(f) Bovine BLG ([214]1b0o ; Wu et al., 1999[215] [Wu, S. Y.,
Perez, M. D., Puyol, P. & Sawyer, L. (1999). J. Biol. Chem. 274,
170-174.]-[216][bluearr.gif] ), buried surface area 484.1 Å2.
The figure was produced with Weblab Viewer Lite (MSI).
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The above figures are
reprinted
by permission from the IUCr:
Acta Crystallogr D Biol Crystallogr
(2002,
58,
480-486)
copyright 2002.
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