A Calcium and Free Fatty Acid-Modulated Protein Kinase as Putative Effector of the Fusicoccin 14-3-3 Receptor

Abstract

Plant cell PMs contain a family of multifunctional H+-ATPases (Sussman, 1994). These H+-ATPases provide the driving force for ion and solute uptake, control the cytoplasmic pH, lower the cell-wall pH to enable cell elongation, and control the activity of voltage-sensitive transporters by means of the electrical membrane potential. In view of these numerous functions, it is not surprising that the activity of the pumps is controlled in a number of ways (Palmgren, 1991). Tight control is exerted by the C terminus of the pump, which acts as an autoinhibitor; a series of phosphorylation sites in this domain are potential control

Calcium Signaling through Protein Kinases. The Arabidopsis Calcium-Dependent Protein Kinase Gene Family

“…Whether there is a plant PKC homolog is still unknown. This observation also may help explain reports of kinases seemingly having properties of both CDPKs and PKC (Abo-el-Saad and Wu, 1995;Van der Hoeven et al, 1996;Lino et al, 1998).…”

Plant Plasma Membrane H+-ATPase in Adaptation of Plants to Abiotic Stresses

“…The results of Urao et al (1994) and Saijo et al (2000) www.intechopen.com demonstrated that NaCl rapidly induced CDPK in different plant tissues. Furthermore, evidence has been presented that Ca 2+ /calmodulin-dependent protein kinases are responsible for the phosphorylation of the plasma membrane H + -ATPase protein (Van der Hoeven et al 1996, Camoni et al, 2000. Ca 2+ has been identified as a possible mediator of ABA-induced stimulus-response coupling (Netting, 2000).…”

Relocation of a Ca 2+ -Dependent Protein Kinase Activity during Pollen Tube Reorientation ���

“…Schaller and co-workers (1992) reported that unlike animal cells, the predominant Ca 2ϩ and lipid-dependent protein kinase associated with the plasma membrane of oat cells has biochemical properties and amino acid sequence unlike PKC. On the 1504 The Plant Cell Relocation of Kinase Activity in Pollen Tubes 1505 other hand, Van der Hoeven et al (1996) detected in oat root plasma membranes a protein kinase that is activated by Ca 2ϩ and cis-unsaturated fatty acids, phosphorylating a synthetic peptide with a motif that can be a target for both PKC and CDPK. Elliot and Kokke (1987) also purified a PKC-type enzyme with dependence on micromolar concentrations of free Ca 2ϩ from seedlings of Amaranthus tricolor.…”

“…H ϩ -ATPases were reported to be present in the apical region of pollen tubes (Feijó et al, 1992) but to be inactive during growth (Feijó et al, 1995). Van der Hoeven et al (1996) have found that H ϩ extrusion activity of oat coleoptiles is inhibited by PKC inhibitors that also decrease the protein kinase activity in plasma membranes vesicles.…”

“…H ϩ -ATPases were reported to be present in the apical region of pollen tubes (Feijó et al, 1992) but to be inactive during growth (Feijó et al, 1995). Van der Hoeven et al (1996) have found that H ϩ extrusion activity of oat coleoptiles is inhibited by PKC inhibitors that also decrease the protein kinase activity in plasma membranes vesicles.In previous reports, we suggested that localized changes in the [Ca 2 ϩ ] c tip-focused gradient should alter the influx of Ca 2 ϩ in specific domains of the dome, in turn modifying vesicle fusion. Based on recent reports of actin distribution in living pollen tubes (Miller et al, 1996), we now extend these suggestions and propose that Golgi vesicles in the extreme apical region are not actually "delivered" to the plasma membrane but have random movements and fuse with the plasma membrane on contact.…”