1kw2

From Proteopedia

CRYSTAL STRUCTURE OF UNCOMPLEXED VITAMIN D-BINDING PROTEIN

PDB ID 1kw2

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Structural highlights

1kw2 is a 2 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.15Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

VTDB_HUMAN Multifunctional protein found in plasma, ascitic fluid, cerebrospinal fluid, and urine and on the surface of many cell types. In plasma, it carries the vitamin D sterols and prevents polymerization of actin by binding its monomers. DBP associates with membrane-bound immunoglobulin on the surface of B-lymphocytes and with IgG Fc receptor on the membranes of T-lymphocytes.

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

Actin is the most abundant protein in eukaryotic cells, but its release from cells into blood vessels can be lethal, being associated with clinical situations including hepatic necrosis and septic shock. A homeostatic mechanism, termed the actin-scavenger system, is responsible for the depolymerization and removal of actin from the circulation. During the first phase of this mechanism, gelsolin severs the actin filaments. In the second phase, the vitamin D-binding protein (DBP) traps the actin monomers, which accelerates their clearance. We have determined the crystal structures of DBP by itself and complexed with actin to 2.1 A resolution. Similar to its homologue serum albumin, DBP consists of three related domains. Yet, in DBP a strikingly different organization of the domains gives rise to a large actin-binding cavity. After complex formation the three domains of DBP move slightly to "clamp" onto actin subdomain 3 and to a lesser extent subdomain 1. Contacts between actin and DBP throughout their extensive 3,454-A(2) intermolecular interface involve a mixture of hydrophobic, electrostatic, and solvent-mediated interactions. The area of actin covered by DBP within the complex approximately equals the sum of those covered by gelsolin and profilin. Moreover, certain interactions of DBP with actin mirror those observed in the actin-gelsolin complex, which may explain how DBP can compete effectively with gelsolin for actin binding. Formation of the strong actin-DBP complex proceeds with limited conformational changes to both proteins, demonstrating how DBP has evolved to become an effective actin-scavenger protein.

Crystal structures of the vitamin D-binding protein and its complex with actin: structural basis of the actin-scavenger system.,Otterbein LR, Cosio C, Graceffa P, Dominguez R Proc Natl Acad Sci U S A. 2002 Jun 11;99(12):8003-8. Epub 2002 Jun 4. PMID:12048248^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Otterbein LR, Cosio C, Graceffa P, Dominguez R. Crystal structures of the vitamin D-binding protein and its complex with actin: structural basis of the actin-scavenger system. Proc Natl Acad Sci U S A. 2002 Jun 11;99(12):8003-8. Epub 2002 Jun 4. PMID:12048248 doi:http://dx.doi.org/10.1073/pnas.122126299