View source for 6tb2


==Structure of human haptoglobin-hemoglobin bound to S. aureus IsdH==
<StructureSection load='6tb2' size='340' side='right'caption='[[6tb2]], [[Resolution|resolution]] 2.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6tb2]] is a 5 chain structure with sequence from [http://en.wikipedia.org/wiki/ ] and [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6TB2 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6TB2 FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=HEM:PROTOPORPHYRIN+IX+CONTAINING+FE'>HEM</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6tb2 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6tb2 OCA], [http://pdbe.org/6tb2 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6tb2 RCSB], [http://www.ebi.ac.uk/pdbsum/6tb2 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6tb2 ProSAT]</span></td></tr>
</table>
== Disease ==
[[http://www.uniprot.org/uniprot/HBA_HUMAN HBA_HUMAN]] Defects in HBA1 may be a cause of Heinz body anemias (HEIBAN) [MIM:[http://omim.org/entry/140700 140700]]. This is a form of non-spherocytic hemolytic anemia of Dacie type 1. After splenectomy, which has little benefit, basophilic inclusions called Heinz bodies are demonstrable in the erythrocytes. Before splenectomy, diffuse or punctate basophilia may be evident. Most of these cases are probably instances of hemoglobinopathy. The hemoglobin demonstrates heat lability. Heinz bodies are observed also with the Ivemark syndrome (asplenia with cardiovascular anomalies) and with glutathione peroxidase deficiency.<ref>PMID:2833478</ref>   Defects in HBA1 are the cause of alpha-thalassemia (A-THAL) [MIM:[http://omim.org/entry/604131 604131]]. The thalassemias are the most common monogenic diseases and occur mostly in Mediterranean and Southeast Asian populations. The hallmark of alpha-thalassemia is an imbalance in globin-chain production in the adult HbA molecule. The level of alpha chain production can range from none to very nearly normal levels. Deletion of both copies of each of the two alpha-globin genes causes alpha(0)-thalassemia, also known as homozygous alpha thalassemia. Due to the complete absence of alpha chains, the predominant fetal hemoglobin is a tetramer of gamma-chains (Bart hemoglobin) that has essentially no oxygen carrying capacity. This causes oxygen starvation in the fetal tissues leading to prenatal lethality or early neonatal death. The loss of three alpha genes results in high levels of a tetramer of four beta chains (hemoglobin H), causing a severe and life-threatening anemia known as hemoglobin H disease. Untreated, most patients die in childhood or early adolescence. The loss of two alpha genes results in mild alpha-thalassemia, also known as heterozygous alpha-thalassemia. Affected individuals have small red cells and a mild anemia (microcytosis). If three of the four alpha-globin genes are functional, individuals are completely asymptomatic. Some rare forms of alpha-thalassemia are due to point mutations (non-deletional alpha-thalassemia). The thalassemic phenotype is due to unstable globin alpha chains that are rapidly catabolized prior to formation of the alpha-beta heterotetramers.  Note=Alpha(0)-thalassemia is associated with non-immune hydrops fetalis, a generalized edema of the fetus with fluid accumulation in the body cavities due to non-immune causes. Non-immune hydrops fetalis is not a diagnosis in itself but a symptom, a feature of many genetic disorders, and the end-stage of a wide variety of disorders.  Defects in HBA1 are the cause of hemoglobin H disease (HBH) [MIM:[http://omim.org/entry/613978 613978]]. HBH is a form of alpha-thalassemia due to the loss of three alpha genes. This results in high levels of a tetramer of four beta chains (hemoglobin H), causing a severe and life-threatening anemia. Untreated, most patients die in childhood or early adolescence.<ref>PMID:10569720</ref>  [[http://www.uniprot.org/uniprot/HPT_HUMAN HPT_HUMAN]] The disease is caused by mutations affecting the gene represented in this entry. [[http://www.uniprot.org/uniprot/HBB_HUMAN HBB_HUMAN]] Defects in HBB may be a cause of Heinz body anemias (HEIBAN) [MIM:[http://omim.org/entry/140700 140700]]. This is a form of non-spherocytic hemolytic anemia of Dacie type 1. After splenectomy, which has little benefit, basophilic inclusions called Heinz bodies are demonstrable in the erythrocytes. Before splenectomy, diffuse or punctate basophilia may be evident. Most of these cases are probably instances of hemoglobinopathy. The hemoglobin demonstrates heat lability. Heinz bodies are observed also with the Ivemark syndrome (asplenia with cardiovascular anomalies) and with glutathione peroxidase deficiency.<ref>PMID:186485</ref> <ref>PMID:6259091</ref> <ref>PMID:2599881</ref> <ref>PMID:8704193</ref>   Defects in HBB are the cause of beta-thalassemia (B-THAL) [MIM:[http://omim.org/entry/613985 613985]]. A form of thalassemia. Thalassemias are common monogenic diseases occurring mostly in Mediterranean and Southeast Asian populations. The hallmark of beta-thalassemia is an imbalance in globin-chain production in the adult HbA molecule. Absence of beta chain causes beta(0)-thalassemia, while reduced amounts of detectable beta globin causes beta(+)-thalassemia. In the severe forms of beta-thalassemia, the excess alpha globin chains accumulate in the developing erythroid precursors in the marrow. Their deposition leads to a vast increase in erythroid apoptosis that in turn causes ineffective erythropoiesis and severe microcytic hypochromic anemia. Clinically, beta-thalassemia is divided into thalassemia major which is transfusion dependent, thalassemia intermedia (of intermediate severity), and thalassemia minor that is asymptomatic.<ref>PMID:1971109</ref>   Defects in HBB are the cause of sickle cell anemia (SKCA) [MIM:[http://omim.org/entry/603903 603903]]; also known as sickle cell disease. Sickle cell anemia is characterized by abnormally shaped red cells resulting in chronic anemia and periodic episodes of pain, serious infections and damage to vital organs. Normal red blood cells are round and flexible and flow easily through blood vessels, but in sickle cell anemia, the abnormal hemoglobin (called Hb S) causes red blood cells to become stiff. They are C-shaped and resembles a sickle. These stiffer red blood cells can led to microvascular occlusion thus cutting off the blood supply to nearby tissues.  Defects in HBB are the cause of beta-thalassemia dominant inclusion body type (B-THALIB) [MIM:[http://omim.org/entry/603902 603902]]. An autosomal dominant form of beta thalassemia characterized by moderate anemia, lifelong jaundice, cholelithiasis and splenomegaly, marked morphologic changes in the red cells, erythroid hyperplasia of the bone marrow with increased numbers of multinucleate red cell precursors, and the presence of large inclusion bodies in the normoblasts, both in the marrow and in the peripheral blood after splenectomy.<ref>PMID:1971109</ref>  
== Function ==
[[http://www.uniprot.org/uniprot/HBA_HUMAN HBA_HUMAN]] Involved in oxygen transport from the lung to the various peripheral tissues. [[http://www.uniprot.org/uniprot/HPT_HUMAN HPT_HUMAN]] As a result of hemolysis, hemoglobin is found to accumulate in the kidney and is secreted in the urine. Haptoglobin captures, and combines with free plasma hemoglobin to allow hepatic recycling of heme iron and to prevent kidney damage. Haptoglobin also acts as an Antimicrobial; Antioxidant, has antibacterial activity and plays a role in modulating many aspects of the acute phase response. Hemoglobin/haptoglobin complexes are rapidely cleared by the macrophage CD163 scavenger receptor expressed on the surface of liver Kupfer cells through an endocytic lysosomal degradation pathway.<ref>PMID:21248165</ref>   Uncleaved haptoglogin, also known as zonulin, plays a role in intestinal permeability, allowing intercellular tight junction disassembly, and controlling the equilibrium between tolerance and immunity to non-self antigens.<ref>PMID:21248165</ref>  [[http://www.uniprot.org/uniprot/HBB_HUMAN HBB_HUMAN]] Involved in oxygen transport from the lung to the various peripheral tissues.<ref>PMID:16904236</ref>   LVV-hemorphin-7 potentiates the activity of bradykinin, causing a decrease in blood pressure.<ref>PMID:16904236</ref>  
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Andersen, C B.F]]
[[Category: Mikkelsen, J H]]
[[Category: Heme acquisition]]
[[Category: Hemoglobin receptor]]
[[Category: Inhibitor]]
[[Category: Metal transport]]