High impact information on CBL1

• We propose a model in which the CBL1/9-CIPK23 pathway ensures activation of AKT1 and enhanced K+ uptake under low-K+ conditions [1].
• PI-4Kbeta1 interacts with RabA4b through a novel homology domain, specific to eukaryotic type IIIbeta PI-4Ks, and PI-4Kbeta1 also interacts with a Ca2+ sensor, AtCBL1, through its NH2 terminus [2].
• The calcium sensor calcineurin B-like 9 modulates abscisic acid sensitivity and biosynthesis in Arabidopsis [3].
• A member of the family, CBL1, is highly inducible by multiple stress signals, implicating CBL1 in stress response pathways [4].
• Here, we show that CIPK3, a Ser/Thr protein kinase that associates with a calcineurin B-like calcium sensor, regulates ABA response during seed germination and ABA- and stress-induced gene expression in Arabidopsis [5].

Biological context of CBL1

• Mutation of CBL1 impairs plant responses to drought and salt stresses and affects gene expression of cold-regulated genes, but does not affect abscisic acid (ABA) responsiveness [6].
• Our data suggest that AtCBL1 may act as a regulatory subunit of a plant calcineurin-like activity mediating calcium signaling under certain stress conditions [7].
• Interaction of AtCBL1 and rat calcineurin A complemented the salt-sensitive phenotype in a yeast calcineurin B mutant [7].
• These findings suggest that the CBL/CIPK or SCaBP/PKS signaling pathways recently found in Arabidopsis may also exist in rice and function in cold response in which calcium signal serves as a second messenger [8].
• Sequence analysis indicated that the open reading frame of the OsCK1 gene consists of 1350 bp encoding 449 amino acid residues, which is very similar to a family of calcineurin B-like protein (CBL)-interacting protein kinases (CIPKs) or salt overly sensitive 2 (SOS2)-like protein kinases (PKS) in Arabidopsis [8].

Anatomical context of CBL1

• Physical interaction of CIPK1 with CBL1 and CBL9 targets the kinase to the plasma membrane [9].

Associations of CBL1 with chemical compounds

• We therefore suggest that, by alternative complex formation with either CBL1 or CBL9, the kinase CIPK1 represents a convergence point for ABA-dependent and ABA-independent stress responses [9].
• Earlier genetic analyses revealed three genes encoding two Ca(2+) sensors (CBL1 and CBL9) and their target protein kinase (CIPK23) to be critical for plant growth on low-K media and for stomatal regulation, indicating that these calcium signaling components participate in the low-K response and turgor regulation [10].

Physical interactions of CBL1

• The studies on calcium sensor calcineurin B-like protein (CBL) and CBL interacting protein kinases (CIPK) are limited to Arabidopsis and rice and their functional role is only beginning to emerge [11].

Other interactions of CBL1

• Remarkably, in contrast to the cbl1 mutant and similarly to the cbl9 mutant, loss of CIPK1 function impairs abscisic acid (ABA) responsiveness [9].
• Here we report the molecular characterization of AtCBL (Arabidopsis thaliana calcineurin B-like protein) from Arabidopsis [7].
• Arabidopsis thaliana calcineurin B-like protein (AtCBL2) is a member of a recently identified family of calcineurin B-like calcium-binding proteins in A. thaliana [12].

Analytical, diagnostic and therapeutic context of CBL1

• In this study, we examined the interaction between AtSR1 and six calcineurin B like proteins of Arabidopsis and found that AtSR1 prominently interacts with one of them, AtCBL2, by yeast two-hybrid assay [13].

References