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From Proteopedia
The crystal structure of plant specific calcium binding protein AtCBL2 in complex with the regulatory domain of AtCIPK14
Structural highlights
Function[CNBL2_ARATH] Acts as a calcium sensor. CBL proteins interact with CIPK serine-threonine protein kinases. Binding of a CBL protein to the regulatory NAF domain of a CIPK protein lead to the activation of the kinase in a calcium-dependent manner. Binds four calcium ions per subunit. Mediates the activation of AKT1 by CIPK proteins (CIPK6, CIPK16, and CIPK23) in response to low potassium conditions and in the context of stomatal movement. Mediates the inactivation of the proton pump AHA2 by CIPK11. Probably involved in regulating signaling responses to abscisic acid.[1] [2] [3] [CIPKE_ARATH] CIPK serine-threonine protein kinases interact with CBL proteins. Binding of a CBL protein to the regulatory NAF domain of CIPK protein lead to the activation of the kinase in a calcium-dependent manner (By similarity). 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 PubMedCalcium signals mediate a multitude of plant responses to external stimuli. Calcineurin B-like (CBL) proteins and their target kinases, CBL-interacting protein kinases (CIPKs), represent important relays in plant calcium signaling. CBL interacts with CIPK through a conserved motif (NAF/FISL motif) within the C-terminal regulatory domain. To better understand the functional role of the CBL-CIPK system, we determined the crystal structure of AtCBL2 in complex with the regulatory domain of AtCIPK14 at 1.2 A resolution. The NAF/FISL motif is inserted into a hydrophobic crevice within AtCBL2, accompanied by a large displacement of the helices and loop on the opposite side of the NAF/FISL motif from the C-terminal region, which shields the hydrophobic crevice in free form. Ca(2+) are coordinated within four EF hands in AtCBL2 in bound form. This calcium coordination pattern differs from that in the structure of the SOS3-SOS2 complex previously reported. Structural comparison of the two structures shows that the recognition of CBL by CIPK is performed in a similar manner, but inherent interactions confer binding affinity and specificity. The crystal structure of plant-specific calcium-binding protein AtCBL2 in complex with the regulatory domain of AtCIPK14.,Akaboshi M, Hashimoto H, Ishida H, Saijo S, Koizumi N, Sato M, Shimizu T J Mol Biol. 2008 Mar 14;377(1):246-57. Epub 2008 Jan 11. PMID:18237745[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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