Influence of calcium on blue-light-induced chloroplast movement in Lemna trisulca L.

The presence of calcium is essential for chloroplast movement induced by blue light in Lemna trisulca L. The regulatory role of calcium was confirmed by the inhibition of chloroplast movement by cytochalasin B and trifluoperazine. The calcium concentration in tissues was modified by ethylene glycol-bis(2-aminoethylether)-N,N,N, N-tetraacetic acid (EGTA), the calcium ionophore A23187 and La³⁺. Only a long period of incubation (12h) in EGTA or La³⁺ caused distrubances in chloroplast movement. This indicates that calcium influx is not essential for chloroplast movement. Those conditions that dramatically changed the internal calcium concentration, either applications of calcium ionophore A23187 and EGTA, or ionophore and La³⁺, markedly decreased the amplitude of response to blue-light pulses. This demonstrates that disturbances of chloroplast movement are observable only when internal stores of calcium are affected by Ca²⁺-antagonists. We suggest that the calcium involved in blue-light-induced chloroplast movement is derived from intracellular stores. The addition of Mg²⁺ to EGTA buffer counteracted its effect, indicating that Mg²⁺, as well as Ca²⁺, might possibly be involved in chloroplast movement.Abbreviations EGTA ethylene glycol-bis(2-aminoethylether)-N,N,N,N-tetraacetic acid - Hepes 4(2-hydroxyethyl-1-piperazine) ethanesulfonic acid - A23187 calcium ionophore We express our gratitude to Professor W. Korohoda for valuable critical comments on this paper and stimulating discussion. We also thank Mr. P. Malec for help in preparing the experiment with trifluoperazine and Mr. A. Waloszek for taking the photographs. We are indebted to Mr. Tim Kline (International House, Krakow, Poland) for improving the English style. This research was supported by grant No. 1042/P2/92/03 from the State Committe for Scientific Research.     

Microtubules and cell shaping in the mesophyll ofNigella damascena L.

Summary Cell shaping in the mesophyll ofNigella damascena was investigated with the aim of determining the origin of the arm-like protrusions, which are characteristic of, e.g., arm-palisade cells. It was found that hoops of cell wall were deposited during the early stages of cell expansion. The hoops were interconnected, thus embracing the cells with a wide-meshed net of local wall reinforcement. The pattern of wall deposition in the extra-cellular matrix correlated with a pattern of bands of microtubules in the cortical cytoplasm of the cells. During lateral expansion bulges were forced through the comparatively thin walls of spaces between the meshes, giving rise to the arm-like protrusions. After establishing the cell shape the bands of microtubules disintegrated and cell wall was uniformly deposited. The results are discussed in the context of the mode of cell shaping observed in the mesophyll of other systems and of a previous, classical hypothesis on the origin of arms in mesophyll cells.Abbreviations DAPI 4,6-diamidino-2-phenylindole - EGTA ethylene glycol-bis(-aminoethyl ether) N,N,N,N-tetraacetic acid - FITC fluorescein isothiocyanate - PME phosphate-magnesium-EGTA-buffer     

Localization of calcium on the stigma surface of Ruscus aculeatus L.

By use of chlorotetracycline and X-ray microanalysis it is demonstrated that the receptive surface of the stigma of Ruscus aculeatus is rich in calcium. The high level of calcium is found in the epidermal cells and in the exudate covering the stigma. These results indicate that in vivo, as in vitro, calcium takes part in the regulation of pollen grain germination.Abbreviations CTC chlorotetracycline - EGTA ethylene glycol-bis (-aminoethyl ether)-N,N,N,N-tetraacetic acid     

Calmodulin-like protein from the fern Anemia phyllitidis L. Sw.

Spores and prothallia of the fern Anemia phyllitidis L. Sw. contain a protein which in its physicochemical properties corresponds largely to calmodulin. It shows immunoreactivity with a calmodulin antiserum and activates bovine brain phosphodiesterase. Its content increases during the early processes of light-induced spore germination, indicating that the Ca²⁺-dependence of these processes may be mediated by this protein.Abbreviations EGTA ethylene, glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid - RIA radioimmunoassay     

Analysis of temperature dependence of cytoplasmic streaming using tonoplast-free cells of Characeae

Summary The temperature dependence of cytoplasmic streaming in intact and tonoplast-free cells ofNitellopsis obtusa was studied using a cryomicroscope. The streaming velocity decreases linearly with decrease in the temperature in well-buffered tonoplast-free cells but non-linearly in some intact cells. These results suggest that low temperature causes a disturbance in the homeostasis of calcium and protons, which inhibit cytoplasmic streaming in intact cells.Abbreviations ADP adenosine 5-diphosphate - APW artificial pond water - ATP adenosine 5-triphosphate - EGTA ethylene glycol-bis(-aminoethyl ether)N,N,N-tetraacetic acid - HEPES N-(2-hydroxyethyl)piperazine-N-(2-ethanesulfonic acid) - PIPES piperazine-N, N-bis(2-ethanesulfonic acid) - Tris tris(hydroxymethyl)aminoethane     

Calcium bridges are not load-bearing cell-wall bonds in Avena coleoptiles

I examined the ability of frozen-thawed Avena sativa L. coleoptile sections under applied load to extend in response to the calcium chelators ethyleneglycol-bis-(-aminoethylether)-N,N,N,N-tetraacetic acid (EGTA) and 2-[(20bis-[carboxymethyl] amino-5-methylphenoxy)methyl]-6-methoxy-8-bis [carboxymethyl]aminoquinoline (Quin II). Addition of 5 mM EGTA to weakly buffered (0.1 mM, pH 6.2) solutions of 2(N-morpholino) ethanesulfonic acid (Mes) initiated rapid extension and wall acidification. When the buffer strength was increased (e.g. from 20 to 100 mM Mes, pH 6.2) EGTA did not initiate extension nor did it cause wall acidification. At 5 mM Quin II failed to stimulate cell extension or wall acidification at all buffer molarities tested (0.1 to 100 mM Mes). Both chelators rapidly and effectively removed Ca²⁺ from Avena sections. These data indicate that Ca²⁺ chelation per se does not result in loosening of Avena cells walls. Rather, EGTA promotes wall extension indirectly via wall acidification.Abbreviations EGTA ethyleneglycol-bis-(-aminoethylether)-N,N,N,N-tetraacetic acid - Quin II 2-[(2-bis-[carboxymethyl]amino-5-methylphenoxy)methyl]-6-methoxy-8-bis(carboxymethyl)aminoquinoline - Mes 2(N-morpholino)ethanesulfonic acid     

The role of bacterial attachment in the transformation of cell-wall-regenerating tobacco protoplasts by Agrobacterium tumefaciens

The presence of a newly formed primary cell wall was shown to be required for attachment and subsequent transformation of tobacco leaf protoplasts by Agrobacterium tumefaciens in cocultivation experiments. In these experiments both protoplasts at different stages after their isolation and cell-wall inhibitors were used. The specificity of Agrobacterium attachment was shown by using other kinds of bacteria that did not attach. By diminishing the concentration of divalent cations using ethylenediaminetetraacetic acid, neither attachment nor transformation was found; however, when more specifically the Ca²⁺concentration was lowered by ethylene glycol-bis (-aminoethyl ether)-N,N,N,N-tetraacetic acid, both phenomena occurred. Commercial lectins had no effect on binding, but this observation does not exclude the involvement of other lectins. Protoplasts isolated from various crown-gall callus tissues also developed binding sites, but when they were at the stage of dividing cells, attachment of agrobacteria was no longer observed. In this respect, cells from protoplasts of normal tobacco leaves behaved differently. Even 16 d after protoplast isolation, the dividing cells were still able to bind A. tumefaciens, while transformation was not detected. For transformation of 3-d-old tobacco protoplasts, a minimal co-cultivation period of 24 h was required, while optimal attachment took place within 5 h. It is concluded that the primary cell wall was sufficiently well formed that certain functional receptor molecules were available for attachment of Agrobacterium as the first step of a multistep process leading to the transformation of cells. The expression of bacterial functions required for attachment, moreover, was independent of the presence of Ti-plasmid.Abbreviations ConA concanavalin A - CW calcofluor white - EDTA ethylenediaminetetraacetic acid - EGTA ethylene glycol-bis (-aminoethyl ether)-N,N,N,N-tetraacetic acid - -Man -methyl-d-mannoside     

The Instron technique as a measure of immediate-past wall extensibility

The relationship between the plastic-extensibility values (PEx) obtained in the Instron technique and the growth parameter, wall extensibility () has been evaluated for Avena sativa L. coleoptile cell walls. The possibility that PEx is proportional to the growth rate rather than to has been eliminated by showing that turgor-driven changes in the growth rate do not cause comparable changes in PEx. For Avena coleoptiles, PEx appears to be a measure of the average over the previous 60–90 min rather than a measure of the instantaneous of the growth equation. This is indicated by the fact that while PEx and the growth rate start to change simultaneously after addition of indole-3-acetic acid or KCN, the growth rate reaches a new, constant value 60–90 min before a new plateau value of PEx is obtained. Similar results are obrained with soybean (Glycine max L.) hypocotyl walls, indicating that the relationship between PEx and the parameter is a general one, although the period over which is averaged differs from tissue to tissue. In addition, it is shown that PEx can be measured more than once on the same section; a new potential for plastic extension is regenerated whenever the force vectors are changed even slightly. It is concluded that PEx is a measure of those domains in the wall where a wall-loosening event has occurred which has not been eliminated by further wall synthesis or other biochemical events.Abbreviations and symbols DP Instron plastic compliance - IAA indole-3-acetic acid - PEx Instron plastic extensibility - instantaneous wall extensibility     

Cytoplasmic streaming in the cell model ofNitella

Summary The plasmalemma ofNitella internode was made freely permeable to solutes by treating the cell with detergent and EGTA under plasmolysis. After the treatment, the cytoplasmic streaming was stopped by bathing the cell in a medium lacking ATP. The streaming was reactivated by perfusing the exterior of the permeabilized cell with a medium containing both Mg²⁺ and ATP. The reactivated streaming could be reversibly stopped by depletion of ATP. However, depletion of Mg²⁺ irreversibly inhibited the streaming.Cytochalasin B at 5 g/ml irreversibly inhibited the reactivated streaming within a minute, showing that microfilaments are involved in the streaming.Abbreviations ATP adenosine-5-triphosphoric acid - CB cytochalasin B - CyDTA cyclohexanediamine-N,N-tetraacetic acid - DMSO dimethylsulfooxide - DTT dithiothreitol - EGTA ethyleneglycol-bis(-aminoethylether)-N,N tetraacetic acid - PIPES piperazine-N,N-bis(2-ethanesulfonic acid) - PMSF phenylmethyl-sulfonylfluoride     

The role of calcium ions in phytochrome-mediated germination of spores of Onoclea sensibilis L.

Phytochrome is confirmed to be the photoreceptor pigment in the germination response of Onoclea sensibilis L. by demonstrating red-far-red (R-FR) photoreversibility. External Ca²⁺ is required for this response with a threshold at a submicromolar concentration. Ethylene glycol-bis(-amino-ethyl ether)-N,N,N,N-tetraacetic acid, La³⁺ and Co²⁺ reversibly inhibit germination. Lanthanum only inhibits germination when applied before or during irradiation, indicating that the external Ca²⁺ requirement is transient, although in the absence of Ca²⁺ the R-stimulated system remains maximally poised to accept the ion for over 4 h after irradiation. The ability to respond to Ca²⁺ 4.1 h after R-irradiation is not reversed by FR-irradiation, indicating that Ca²⁺ transport has been uncoupled from phytochrome. Barium and Sr²⁺, but not Mg²⁺ can substitute for Ca²⁺. Artificially increasing the concentration of intracellular free Ca²⁺ with the ionophore A 23187 stimulates germination in the dark. The Ca²⁺-calmodulin antagonists, trifluoperizine and chlorpromazine, reversibly inhibit germination. Calcium is required in phytochrome-mediated fern spore germination; it may be acting as a second messenger.Abbreviations EGTA ethylene glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid - FR far-red light - R fed light     

Reconstitution of cytoplasmic streaming inCharaceae

Summary The active sites of actin of oneCharaceae species were found to interact with the endoplasmic factor from a different species. Protoplasm was suqueezed out of cells ofChara australis with vacuoles that had been perfused beforehand with a medium containing EGTA and Mg · ATP. Centrifugation of this protoplasmic mixture divided it into the supernatant composed of endoplasmic granules and the precipitate composed of chloroplasts and nuclei. When the endoplasmic granular aggregates were introduced into a tonoplast-freeNitella axilliformis cell treated with NEM to inactivate the endoplasmic factor, they became attached to theNitella gel and streamed longitudinally with the polarity. Treatment of the endoplasmic granules with the strong Mg²⁺chelator CyDTA (1,2-cyclohexane diamineN, N-tetraacetic acid) irreversibly inhibited reconstitution of the cytoplasmic streaming.Abbreviations APW artificial pond water - ATP adenosine-5-triphosphoric acid - CyDTA cyclohexanediamine-N,N-tetraacetic acid - DTT dithiothreitol - EGTA ethyleneglycol-bis-(-aminoethylether)-N,N-tetraacetic acid - HMM heavy meromyosin - NEM N-ethylmaleimide - PEP phosphoenolypyruvate - PIPES piperazine-N,N-bis-(2-ethane-sulfonic acid) - PK pyruvate kinase - PMSF phenylmethylsulfonylfluoride     

Calcium requirement in nitrogen fixation in the cyanobacterium Synechococcus RF-1

Under diurnal 16/8-h light-dark cycles, ethyleneglycol-bis-(-aminoethyl ether)-N,N,N,N-tetraacetic acid (EGTA) at 1 mM completely blocked the appearance of rhythmic N₂-fixing activity in Synechococcus RF-1. Ca²⁺ at 2 mM, when supplied either together with or several hours after the EGTA application, restored the nitrogenase activity, whereas, when Ca²⁺ was supplied several hours later, the peak of nitrogenase activity was shifted from the dark to the light period in which the activity is normally suppressed. Sr²⁺ also reversed the inhibition by EGTA, but only partially. When O₂ in the gas phase above the culture was below 1%, the inhibition of nitrogenase activity by EGTA was reduced to less than 20% of the control value without EGTA. Thus Ca²⁺ appears to be required by the cell to protect its nitrogenase from inactivation by O₂. In media without EGTA, a close correlation between nitrogenase activity and concentrations of Ca²⁺ was also observed.Abbreviation EGTA ethyleneglycol-bis-(-aminoethyl ether)-N,N,N,N-tetraacetic acid     

Pectins as mediators of wall porosity in soybean cells

The non-invasive technique of fluorescence redistribution after photobleaching was employed on soybean (Glycine max (L.) Merr.) root cells grown in suspension culture to examine macromolecular transport across plant cell walls. Using both fluorescently derivatized dextrans and proteins of graded size, a functional range of diameters for putative trans-wall channels was determined to be 6.6–8.6 nm. A mild treatment with pectinase apparently enlarged the channels, without adversely affecting cell viability, enabling significantly larger molecules to pass through the wall. Treatment of the cells with cellulysin or protease did not have this enlargement effect. It appears that the organization of pectic substances is a major control element in defining the sieving properties of the wall.Abbreviations EDTA ethylenediaminetetraacetic acid - EGTA ethylene glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid - Fl-dextran fluorescein-derivatized dextran - FRAP fluorescence redistribution after photobleaching - kDa kilodalton     

The arrangement of F-actin and microtubules during germination of Mucor rouxii sporangiospores

The distribution of F-actin microfilaments and microtubules was analyzed in germinating sporangiospores of Mucor rouxii by labeling with rhodamine-tagged phalloidin and by immunofluorescence microscopy. The transition from isodiametrical to apical growth was accompanied by a switch from uniform distribution of F-actin patches to a polarized accumulation of F-actin material at the germ tube tips. Immunoblotting of cell-free extracts of M. rouxii with a monoclonal anti-porcine -tubulin antibody (TU-01) disclosed two discrete bands of -tubulin suggesting the existence of two -tubulin genes in this fungus. Immunofluorescence microscopy of germinating cells stained with the same antibody revealed an elaborate network of cytoplasmic microtubules that persisted during the entire germination process and extended into the apex of the germ tube. Although their precise roles remain undetermined, the observed arrangement of cytoskeletal elements during germination is consistent with their presumed involvement in cell wall morphogenesis: the long axial microtubules serving as long-distance conveyors of wall-building vesicles to the apical region while the concentrated F-actin patches mark the participation of microfilaments in the zone of intense vesicle exocytosis at the hyphal apex.Abbreviations DAPI 4,6-diamidino-2-phenylindole - DTT dithiothreitol - EGTA Ethylene glycol-bis (beta-aminoethyl ether) - N,N,N,N tetraacetic acid - F-actin Filamentous actin - MES 2-(N0morpholino)-ethanesulfonic acid - PIPES Piperazine-N,N-bis-2-ethanesulfonic acid - PMSF Phenyl-methylsulphonyl fluoride - TBS Tris-buffered saline     

Calcium restriction induces cardenolide accumulation in cell suspension cultures of Digitalis thapsi L.

Summary The removal of calcium ions from Murashige and Skoog culture medium induced a marked increase in the accumulation of cardenolides in cell suspension cultures of Digitalis thapsi. Cell viability was not affected although growth was slightly reduced. Strontium ions could substitute for calcium in inhibiting cardenolide production, this effect of calcium being reversed by the addition of LaCl₃ or ethyleneglycol-bis-(-aminoethyl ether)-N,N-tetraacetic acid. The results suggest that calcium, apart from its general effects on growth, may play a role in the regulation of cardenolide metabolism in a concentration dependent manner.Abbreviations BA 6-benzylaminopurine - 2 4-D 2,4-dichlorophenoxyacetic acid - EGTA ethyleneglycol-bis-(-aminoethyl ether)-N,N-tetraacetic acid - FW fresh weight - MS Murashige and Skoog (1962)     

Electric fields affect the orientation of cortical microtubules and cell expansion in pea callus

Summary Cortical microtubules in callus derived fromPisum sativum roots form parallel arrays within cells but are randomly oriented across the tissue. These arrays align perpendicular to the direction of an applied electric field of 6 mV per cell. Application of a field of 6 mV per cell for 4 days resulted in the co-ordinated expansion of cells parallel to the field direction. Cortical microtubule arrays were still aligned perpendicular to the applied field 24 h after removal of the field. The imposition of a field to callus after the removal of cortical microtubules by oryzalin and in the presence of the herbicide resulted in the orientation of recovering microtubules perpendicular to the direction of the field, indicating that microtubules are not directly involved in the detection of the field.Abbreviations EGTA ethylene glycol-bis (-aminoethyl ether) N,N,N-tetraacetic acid - FITC fluorescein isothiocyanate - MSB microtubule stabilising buffer - PIPES piperazine-N,N-bis(2-ethanesulphonic acid) - oryzalin 3,5-dinitro-N⁴,N⁴ dipropylsulphanil-amide     

Calcium-mediated changes in peroxidase and O-diphenol oxidase activities of cotton fibres (Gossypium spp.) and its possible relationship to ABA

This work is an investigation of the influence of ABA and calcium on soluble and wall-bound activities of peroxidase and O-diphenol oxidase of cotton fibres at the stages of primary and secondary wall development, during incubation of intact fibres for 3h at 28°C. ABA (10 M) caused marked inhibition of enzyme activities in both the fractions, whereas calcium (1 mM) was promotory. The incorporation of 1 mM EGTA (a calcium chelator) and chlorpromazine (10 g cm^–3) (a calmodulin antagonist) resulted in decreased enzyme activities suggesting regulation of enzyme synthesis and/or secretion to the cell wall by calcium-calmodulin. As a general trend, the relative effect of Ca²⁺ on the activity of peroxidase in the wall was much greater than on the soluble activity, but this was not true of O-diphenol oxidase. It is inferred that ABA inhibits enzymic activities by inhibiting calmodulin synthesis or its mobilization to sites of action.Abbreviations ABA abscisic acid - EGTA ethylene glycol-bis( amino-ethyl ether)N,N tetraacetic acid - DAA days after anthesis     

Physical properties of the cell wall of photoautotrophic suspension cells fromChenopodium rubrum L.

Photoautotrophic suspension cells ofChenopodium rubrum were used to determine Donnan potential, charge density and pore-radius distribution in the cell wall. Experiments were done either with turgescent cells or with isolated cell walls. Titration of a cell-wall-generated 9-aminoacridine fluorescence quench with salts of mono- and divalent cations was used to determine Donnan potential and charge density. The experiments and theory were adapted from measurements of membrane surface charges. A tenfold increase in ionic strength, which decreases the repellant forces between charges of the same sign, led to an approximately threefold increase in the measured charge density, thus resulting in a much smaller decrease of the Donnan potential than would be expected if the charge density remained fixed. This decreased influence of ionic strength on the Donnan potential, resulting from the elasticity of the cell wall, was also measurable but less pronounced when the wall of intact cells was stretched by turgor. The porosity of the cell wall was determined by longterm uptake of polyethylene glycols of different molecular weights, and by gel filtration of polyethylene glycols and dextrans as well as mono- and disaccharides using intact suspension cells as matrix. Both methods gave a mean pore diameter of about 4.5 nm and a maximum pore size of 5.5 nm. The resulting pores-size distribution was slightly broader with the latter method.Abbreviations 9-AA 9-aminoacridine - DMBr₂ decamethoniumbromide=N,N,N,N,N,N hexamethyldecane-1,10-diaminebromide - DW dry weight after lyophilization - EDTA ethylene diaminetetra acetic acid - EGTA ethylene glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid - FW fresh weight - Mops 3-(N-morpholino)propanesulfonic acid - MW molecular weight - PEG polyethylene glycol     

Changes in the organization of the tubulin cytoskeleton during the early stages of<Emphasis Type="Italic"> Solanum lycopersicoides</Emphasis> Dun. protoplast culture

Changes in the tubulin cytoskeleton during protoplast culture and plant regeneration of Solanum lycopersicoides Dun. were analyzed using an immunodetection method. Directly after isolation, four groups of protoplasts were distinguished: (1) mononuclear, (2) polynuclear, (3) homogeneous, (4) anuclear. The tubulin cytoskeleton of the protoplasts underwent rearrangements, correlating to the number and structure of cell nuclei in the protoplast. All protoplast groups with the exception of mononuclear were characterized by perturbations in the organization of the tubulin cytoskeleton. Anuclear and homogeneous protoplasts did not have a tubulin cytoskeleton. Polynuclear protoplasts had cortical microtubules, but were not capable of re-forming their original arrangement and did not possess a radial or perinuclear cytoskeleton. Irregularities in microtubule arrangement of these three groups of protoplasts caused their inability to regenerate a cell wall and to divide. Anuclear, polynuclear and homogeneous protoplasts were eliminated from the culture. Mononuclear protoplasts rearranged their cortical microtubules and reestablished the radial and perinuclear tubulin cytoskeleton. Re-formation of the cell suspension and subsequent regeneration of plants occurred exclusively from mononuclear protoplasts, which were able to regenerate cell walls and to divide.Abbreviations 2,4D 2,4-Dichlorophenoxyacetic acid - BA Benzyloadenine - DAPI 4,6 Diamidino-2-phenylindole - DMSO Dimethyl sulfoxide - EGTA Ethylene glycol-bis(2-aminoethylether)-N, N, N, N-tetraacetic acid - FITC Fluorescein isothiocyanate - MS Murashige and Skoog medium - MSB Microtubule stabilizing buffer - PBS Phosphate-buffered saline - PIPES Piperazine-N, N-bis(2-ethane sulfonic acid) - PPB Preprophase bandCommunicated by H. Lörz     

Calcium-dependent protein kinase from apple fruit membranes is calmodulin-independent but has calmodulin-like properties

Crude Ca²⁺-activated protein kinase from membranes of apple (Malus domestica L. Borkh., Cox's Orange Pippin) fruit can be partially purified to yield a Ca²⁺-dependent protein kinase whose activity is apparently not regulated by calmodulin. The autophosphorylating catalytic subunit of this protein kinase shows a Ca²⁺-dependent mobility shift of approx. 10 kilodaltons (kDa) on sodium dodecyl sulphate-polyacrylamide gel electrophoresis; in the absence of added Ca²⁺ or ethylene glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid (EGTA) its apparent molecular mass is approx. 50 kDa. The Ca²⁺-dependent protein kinase is inhibited by the calmodulin antagonists N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide and trifluoperazine with IC₅₀ values of approx. 45 M and 15 M, respectively. These similarities between the protein kinase and calmodulin indicate that the kinase may be a calmodulin-like protein.Abbreviations DEAE diethylaminoethyl - EGTA ethylene glycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid - Hepes 4-(-2-hydroxyethyl)-1-piperazineethanesulphonic acid - kDa kilodalton - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecyl sulphate - W7 N-(6-aminohexyl)-5-chloro-1-naphthalenesulphonamide - W5 N-(6-aminohexyl)-naphthalenesulphonamide