2eyn: Difference between revisions

[[Image:2eyn.gif|left|200px]]<br /><applet load="2eyn" size="350" color="white" frame="true" align="right" spinBox="true"  

Alpha-actinin belongs to the spectrin family of actin crosslinking and bundling proteins that function as key regulators of cell motility, morphology and adhesion. The actin-binding domain (ABD) of these proteins consists of two consecutive calponin homology (CH) domains. Electron microscopy studies on ABDs appear to support two competing actin-binding models, extended and compact, whereas the crystal structures typically display a compact conformation. We have determined the 1.7A resolution structure of the ABD of alpha-actinin 1, a ubiquitously expressed isoform. The structure displays the classical compact conformation. We evaluated the two binding models by surface conservation analysis. The results show a conserved surface that spans both domains and corresponds to two previously identified actin-binding sites (ABS2 and ABS3). A third, and probably less important site, ABS1, is mostly buried in the compact conformation. However, a thorough examination of existing structures suggests a weak and semi-polar binding interface between the two CHs, leaving open the possibility of domain reorientation or opening. Our results are consistent with a two-step binding mechanism in which the ABD interacts first in the compact form observed in the structures, and then transitions toward a higher affinity state, possibly through minor rearrangement of the domains.

2EYN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2EYN OCA].  

[[Category: Lee, S H.]]

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