3MC2
Crystal Structure of the Murine Inhibitor of Carbonic Anhydrase
Summary for 3MC2
| Entry DOI | 10.2210/pdb3mc2/pdb |
| Descriptor | Inhibitor of Carbonic Anhydrase (1 entity in total) |
| Functional Keywords | mica, transferrin superfamily, lyase inhibitor |
| Biological source | Mus musculus (mouse) |
| Total number of polymer chains | 4 |
| Total formula weight | 302879.62 |
| Authors | Eckenroth, B.E.,Mason, A.B.,Everse, S.J. (deposition date: 2010-03-26, release date: 2010-07-28, Last modification date: 2024-11-06) |
| Primary citation | Eckenroth, B.E.,Mason, A.B.,McDevitt, M.E.,Lambert, L.A.,Everse, S.J. The structure and evolution of the murine inhibitor of carbonic anhydrase: A member of the transferrin superfamily. Protein Sci., 19:1616-1626, 2010 Cited by PubMed Abstract: The original signature of the transferrin (TF) family of proteins was the ability to bind ferric iron with high affinity in the cleft of each of two homologous lobes. However, in recent years, new family members that do not bind iron have been discovered. One new member is the inhibitor of carbonic anhydrase (ICA), which as its name indicates, binds to and strongly inhibits certain isoforms of carbonic anhydrase. Recently, mouse ICA has been expressed as a recombinant protein in a mammalian cell system. Here, we describe the 2.4 Å structure of mouse ICA from a pseudomerohedral twinned crystal. As predicted, the structure is bilobal, comprised of two α-β domains per lobe typical of the other family members. As with all but insect TFs, the structure includes the unusual reverse γ-turn in each lobe. The structure is consistent with the fact that introduction of two mutations in the N-lobe of murine ICA (mICA) (W124R and S188Y) allowed it to bind iron with high affinity. Unexpectedly, both lobes of the mICA were found in the closed conformation usually associated with presence of iron in the cleft, and making the structure most similar to diferric pig TF. Two new ICA family members (guinea pig and horse) were identified from genomic sequences and used in evolutionary comparisons. Additionally, a comparison of selection pressure (dN/dS) on functional residues reveals some interesting insights into the evolution of the TF family including that the N-lobe of lactoferrin may be in the process of eliminating its iron binding function. PubMed: 20572014DOI: 10.1002/pro.439 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.4 Å) |
Structure validation
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