1anx | pdb_00001anx
THE CRYSTAL STRUCTURE OF A NEW HIGH-CALCIUM FORM OF ANNEXIN V
Structural highlights
Disease[ANXA5_HUMAN] Defects in ANXA5 are associated with susceptibility to pregnancy loss, recurrent, type 3 (RPRGL3) [MIM:614391]. A common complication of pregnancy, resulting in spontaneous abortion before the fetus has reached viability. The term includes all miscarriages from the time of conception until 24 weeks of gestation. Recurrent pregnancy loss is defined as 3 or more consecutive spontaneous abortions.[1] Function[ANXA5_HUMAN] This protein is an anticoagulant protein that acts as an indirect inhibitor of the thromboplastin-specific complex, which is involved in the blood coagulation cascade. 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 PubMedAnnexin V was crystallized in the presence of a high concentration of calcium and the structure refined at 1.9 A resolution. The crystals are triclinic (P1) with three molecules per asymmetric unit and pseudo-R3 symmetry, reflecting a tendency of annexin to form trimers. The overall structure of the protein is similar to that seen in other crystal forms. There are, however, significant changes in domain III, where a new calcium site is formed. The whole region surrounding this site is reorganized in our structure, rendering annexin V more symmetrical and more alike annexin I. The formation of the new calcium site causes the displacement of Trp187 from a buried to an exposed conformation, a change that has recently been demonstrated by fluorescence measurements. The affinity of the different potential calcium sites is modulated: there is no calcium bound in domains II and IV, while up to two secondary calcium ions sites (in domains I and III) can substitute, depending on the calcium concentration present. We suggest that annexin can act as a calcium buffer, binding or releasing calcium depending on its local concentration. Our results also show that annexin displays inherent mobility which, together with its capacity to modulate the calcium affinity of its sites, can be of importance for its function on the membrane surface. The crystal structure of a new high-calcium form of annexin V.,Sopkova J, Renouard M, Lewit-Bentley A J Mol Biol. 1993 Dec 5;234(3):816-25. PMID:8254674[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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