1EXS

STRUCTURE OF PORCINE BETA-LACTOGLOBULIN

Summary for 1EXS

• Entry DOI: 10.2210/pdb1exs/pdb
• Descriptor: BETA-LACTOGLOBULIN, SODIUM ION, GLYCEROL, ... (4 entities in total)
• Functional Keywords: lipocalin fold, lipid-binding protein, lipid binding protein
• Biological source: Sus scrofa (pig)
• Cellular location: Secreted: P04119
• Total number of polymer chains: 1
• Total formula weight: 17997.55

Authors

Abrahams, J.P.,Hoedemaeker, F.J. (deposition date: 2000-05-04, release date: 2000-11-15, Last modification date: 2024-11-06)

Primary citation

Hoedemaeker, F.J.,Visschers, R.W.,Alting, A.C.,de Kruif, K.G.,Kuil, M.E.,Abrahams, J.P.
A novel pH-dependent dimerization motif in beta-lactoglobulin from pig (Sus scrofa).
Acta Crystallogr.,Sect.D, 58:480-486, 2002

PubMed Abstract: 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.

PubMed: 11856834
DOI: 10.1107/S0907444902000616

Experimental method

X-RAY DIFFRACTION (2.39 Å)