1qh4: Difference between revisions

[[Image:1qh4.gif|left|200px]]<br /><applet load="1qh4" size="350" color="white" frame="true" align="right" spinBox="true"  

Excitable cells and tissues like muscle or brain show a highly fluctuating consumption of ATP, which is efficiently regenerated from a large pool of phosphocreatine by the enzyme creatine kinase (CK). The enzyme exists in tissue--as well as compartment-specific isoforms. Numerous pathologies are related to the CK system: CK is found to be overexpressed in a wide range of solid tumors, whereas functional impairment of CK leads to a deterioration in energy metabolism, which is phenotypic for many neurodegenerative and age-related diseases. The crystal structure of chicken cytosolic brain-type creatine kinase (BB-CK) has been solved to 1.41 A resolution by molecular replacement. It represents the most accurately determined structure in the family of guanidino kinases. Except for the N-terminal region (2-12), the structures of both monomers in the biological dimer are very similar and closely resemble those of the other known structures in the family. Specific Ca2+-mediated interactions, found between two dimers in the asymmetric unit, result in structurally independent heterodimers differing in their N-terminal conformation and secondary structure. The high-resolution structure of BB-CK presented in this work will assist in designing new experiments to reveal the molecular basis of the multiple isoform-specific properties of CK, especially regarding different subcellular locations and functional interactions with other proteins. The rather similar fold shared by all known guanidino kinase structures suggests a model for the transition state complex of BB-CK analogous to the one of arginine kinase (AK). Accordingly, we have modeled a putative conformation of CK in the transition state that requires a rigid body movement of the entire N-terminal domain by rms 4 A from the structure without substrates.

1QH4 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus] with <scene name='pdbligand=CA:'>CA</scene> and <scene name='pdbligand=ACT:'>ACT</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Creatine_kinase Creatine kinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.3.2 2.7.3.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QH4 OCA].  

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