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Analysis of the recently completed Arabidopsis ge-nome sequence indicates that ϳ31% of the predicted genes could not be assigned to functional categories, as they do not show any sequence similarity with proteins of known function from other organisms. Calmodulin (CaM), a ubiquitous and multifunctional Ca 2؉ sensor, interacts with a wide variety of cellular(More)
BACKGROUND In plants, calcium (Ca2+) has emerged as an important messenger mediating the action of many hormonal and environmental signals, including biotic and abiotic stresses. Many different signals raise cytosolic calcium concentration ([Ca2+]cyt), which in turn is thought to regulate cellular and developmental processes via Ca2+-binding proteins. Three(More)
Calmodulin (CaM) plays an important role in sensing and transducing changes in cellular Ca2+ concentration in response to several biotic and abiotic stresses. Although CaM is implicated in plant-pathogen interactions, its molecular targets and their role in defense signaling pathway(s) are poorly understood. To elucidate the signaling pathways that link CaM(More)
second messenger in eukaryotes, and calmodulin regulate some kinesins by causing the motor to dissociate from its biological track, the microtubule. Our focus was the mechanism of calcium regulation of kinesin at atomic resolution. Here we report the crystal structure of kinesin-like calmodulin binding protein (KCBP) from potato resolved to 2.3 Å. The(More)
Calmodulin (CaM), a key calcium sensor in all eukaryotes, regulates diverse cellular processes by interacting with other proteins. To isolate CaM binding proteins involved in ethylene signal transduction, we screened an expression library prepared from ethylene-treated Arabidopsis seedlings with 35S-labeled CaM. A cDNA clone, EICBP (Ethylene-Induced CaM(More)
In Arabidopsis and other plants there are multiple calmodulin isoforms. However, the role of these isoforms in regulating the activity of target proteins is obscure. Here, we analyzed the interaction between a kinesin-like calmodulin-binding motor protein (Reddy, A. S. N., Safadi, F., Narasimhulu, S. B., Golovkin, M., and Hu, X. (1996) J. Biol. Chem. 271,(More)
Ca2+ and calmodulin (CaM), a key Ca2+ sensor in all eukaryotes, have been implicated in defense responses in plants. To elucidate the role of Ca2+ and CaM in defense signaling, we used 35S-labeled CaM to screen expression libraries prepared from tissues that were either treated with an elicitor derived from Phytophthora megasperma or infected with(More)
Plant kinesin-like calmodulin-binding protein (KCBP) is a novel member of the kinesin superfamily that interacts with calmodulin (CaM) via its CaM-binding domain (CBD). Activated CaM (Ca(2+)-CaM) has been shown to inhibit KCBP interaction with microtubules (MTs) thereby abolishing its motor- and MT-dependent ATPase activities. To test whether the fusion of(More)
Kinesins are molecular motors that power cell division and transport of various proteins and organelles. Their motor activity is driven by ATP hydrolysis and depends on interactions with microtubule tracks. Essential steps in kinesin movement rely on controlled alternate binding to and detaching from the microtubules. The conformational changes in the(More)
Functional studies with ZWICHEL (ZWI), which encodes a Ca 2þ-calmodulin-regulated kinesin, have shown its involvement in trichome morphogenesis and cell division. To identify regulatory regions that control the ZWI expression pattern, we generated transgenic Arabidopsis plants with a GUS reporter driven by different lengths of the ZWI gene 5¢ region alone(More)