title: A protein phosphorylation/dephosphorylation network regulates a plant potassium channel.
abstract: Potassium (K(+)) is an essential nutrient for plant growth and development. Plants often adapt to low K(+) conditions by increasing their K(+) uptake capability. Recent studies have led to the identification of a calcium signaling pathway that enables plants to act in this capacity. Calcium is linked to two calcineurin B-like calcium sensors (CBLs) and a target kinase (CBL-interacting protein kinase 23 or CIPK23) that, in turn, appears to phosphorylate and activate the potassium channel, Arabidopsis K(+) transporter 1 (AKT1), responsible for K(+) uptake in roots. Here, we report evidence that this regulatory mechanism is more elaborate than earlier envisaged. The recently described pathway is part of an extensive network whereby several CBLs interact with multiple CIPKs in the activation of the potassium channel, AKT1. The physical interactions among the CBL, CIPK, and AKT1 components provide a mechanism for specifying the members of the CBL and CIPK families functional in AKT1 regulation. The interaction between the CIPKs and AKT1 was found to involve the kinase domain of the CIPK component and the ankyrin repeat domain of the channel. Furthermore, we identified a 2C-type protein phosphatase that physically interacts and inactivates the AKT1 channel. These findings provide evidence that the calcium-sensitive CBL and CIPK families together with 2C-type protein phosphatases form a protein phoshporylation/dephosphorylation network that regulates the AKT1 channel for K(+) transport in plants.
authors: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors: Sung Chul
authors: SC
authors: Lee
authors: Wen-Zhi
authors: WZ
authors: Lan
authors: Beom-Gi
authors: BG
authors: Kim
authors: Legong
authors: L
authors: Li
authors: Yong Hwa
authors: YH
authors: Cheong
authors: Girdhar K
authors: GK
authors: Pandey
authors: Guihua
authors: G
authors: Lu
authors: Bob B
authors: BB
authors: Buchanan
authors: Sheng
authors: S
authors: Luan
mesh_terms: D017360:Arabidopsis / Q000502:physiology; D029681:Arabidopsis Proteins / Q000378:metabolism / Q000502:physiology; D008954:Models, Biological; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010940:Plant Proteins / Q000378:metabolism*; D015221:Potassium Channels / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D010750:Phosphoproteins; D010940:Plant Proteins; D015221:Potassium Channels; C074500:AKT1 protein, Arabidopsis; C507144:CIPK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases