Some Characteristics of Membrane-Associated Protein Kinase in Lemna paucicostata

A protein kinase which phosphorylates histone was isolated fromthe endoplasmic reticulum-rich fractions of Lemna paucicostata.The enzyme could be solubilized by sonication, and its molecularweight was estimated as 220,000 by Sephacryl S-300 gel filtration.The optimum pH for enzyme activity was 9.0–9.5 and theactivity was stimulated by Co^2$, Mg^2$ and Mn^2$. Substrate proteinswhich might be phosphorylated by this protein kinase were alsodetected in microsomal fractions of Lemna plants. ¹ Present address: Advanced Research Laboratory, HITACHI LTD.,Kokubunji, Tokyo 185, Japan.     

Activation Energies of Reactions Catalyzed by the Nitrate Reductase from Chlorella vulgaris

The thermal dependence of two of the reactions catalyzed bythe nitrate reductase from Chlorella vulgaris was determined.The activation energies for NADH:nitrate oxidoreductase (EC1.6.6.1 [EC] ) and NADH:Cytochrome c oxidoreductase (EC 1.6.99.3 [EC] )are 42.1 kJ?mol^–1 and 21.5 kJ?mol^–1, respectively.Since the thermal dependency of the two enzymes is different,ratios of the activities will vary with temperature. The importanceof both rigorous thermal control during nitrate reductase assaysas well as the need to specify the temperature at which theratio of activities for the enzyme are clearly established. ¹Present Address: Cropping Systems Research Laboratory, USDA-ARS,Route 3, Box 215, Lubbock, TX 79401, U.S.A. (Received November 25, 1987; Accepted March 2, 1988)     

The Deduced Amino Acid Sequence of Phytochrome from Adiantum Includes Consensus Motifs Present in Phytochrome B from Seed Plants

A cDNA for the phytochrome of the fern Adiantum capillus-venerisL. was cloned and sequenced. The deduced phytochrome is 50{smalltilde}55% identical to phytochromes of seed plants, and 68%identical to Selaginella phytochrome. Regions resemble thosein previously characterized phytochromes from ferns, lower plantsand seed plants. ³Present address: Yamanouchi Pharmaceutical Co., Ltd., 21 Miyukigaoka,Tsukuba-shi, Ibaraki, 305 Japan ⁴Present address: Plant Growth Regulation Laboratory, The Instituteof Physical and Chemical Research (RIKEN), Hirosawa 2-1, Wako-shi,Saitama, 351-01 Japan ⁵Present address: Advanced Research Laboratory, Hitachi, Ltd.,Hatoyama, Saitama, 350-03 Japan     

Effect of temperature on the ethylene-synthesizing systems in apple, tomato and Penicillium digitatum

Arrhenius plots of ethylene-synthesizing systems of apple andtomato showed discontinuities while the plot for Penicilliumdigitatum was linear. Triton X-100 markedly lowered the activationenergies of the apple and tomato systems without altering thatof the fungal system. The data presented suggest that the lipidmicro-environment of the ethylene-synthesizing enzyme systemsin higher plants and P. digitatum are different, and that cellmembrane-cell wall complex may be the site of ethylene-synthesizingenzymic systems in higher plants. ¹ On leave from the M. S. University of Baroda, India. ² On leave from the Agricultural Research Organization, TheVolcani Center, Israel. (Received February 7, 1977; )     

Enzymes involved in the last steps of the biosynthesis of mannitol in brown algae

Mannitol-1-phosphate dehydrogenase (EC 1.1.1.17 [EC] ) and mannitol-1-phosphatase(EC number yet unassigned) were detected in the brown algae,Spatoglossum pacificum and Dictyota dichotoma. The enzymes wereextracted from algal fronds and their properties were investigatedusing partially purified preparations. Mannitol-1-phosphatase shows maximum activity at pH 7. The enzymehad a narrow substrate specificity. The Km value for mannitol-1-phosphateis 8.3x10^–4 M (30°C, pH 7.0). The enzyme is activatedby Mg⁺⁺ and Mn⁺⁺and is strongly inhibited by PCMB, Hg⁺⁺and NaF. Mannitol-1-phosphate dehydrogenase showed maximum activitiesat pH values 6.5 and 10.2 in reductive and oxidative reactions,respectively. The dehydrogenase also showed narrow substratespecificity; mannitol-1-phosphate and NAD or fructose-6-phosphateand NADH₂ are utilized, respectively, in oxidative and reductivereactions by the enzyme. Km values for these substrates andthe coenzymes are 2.5x10^–4 M and 7.1x10^–5 M forthe first pair and 2.8x10^–4 M and 1.3x10^–5 M forthe latter pair. This enzyme was strongly inhibited by PCMBand Hg⁺⁺, but was only slightly affected by adenosine phosphates. Possible roles of these enzymes in the biosynthesis of mannitolin brown algae are discussed. ¹ Contributions from the Shimoda Marine Biological Station ofTokyo Kyoiku University, No. 233. This work was supported inpart by a Grant-in-Aid for Co-operative Research from the Ministryof Education, Japan and in part by a grant to one of us (T.Ikawa) from the Matsunaga Science Foundation. ² Present address: Chemical and Physical Laboratory, HoechstJapan Research Laboratory, Minamidai, Kawagoe, Japan. (Received February 22, 1972; )     

Purification and Characterization of a Ca2+-Dependent Protein Kinase from the Halotolerant Green Alga Dunaliella tertiolecta

A Ca²⁺-dependent protein kinase (CDPK) that has been partiallypurified and characterized previously [Yuasa and Muto (1992)Arch. Biochem. Biophys. 296: 175] was further purified to about20,000-fold from the soluble fraction of Dunaliella tertiolecta.The enzyme preparation contained 60- and 52-kDa polypeptidesboth of which phosphorylated casein as a substrate. Both polypeptidesshowed a Ca²⁺-dependent increase in mobility during SDS-PAGEand ⁴⁵Ca²⁺-binding activity after SDS-PAGE and electroblottingonto a nitrocellulose membrane, suggesting that both the 60-and 52-kDa CDPKs directly bind Ca²⁺. The protein kinase inhibitors,K-252a and staurosporine, inhibited the CDPK competitively withrespect to ATP. An antibody raised against the 60-kDa CDPK crossreactedwith both the 60- and 52-kDa polypeptides. Both molecular specieswere autophosphorylated in the presence of Ca²⁺, and a highlyphosphorylated 80-kDa band appeared in addition to these phosphorylatedbands at 60 and 52 kDa in SDS-PAGE. However, the specific activityof CDPK was not changed by prior autophosphorylation when theautophosphorylated enzyme was assayed as a mixture of thesephosphorylated molecular species. Only the 60-kDa polypeptidewas immunodetected in subcellular fractions of Dunaliella cells.The 52-kDa polypeptide increased during storage of the enzyme.These results suggest that the 52-kDa polypeptide is a proteolyticartifact produced during purification. Immunoreactive bandsof 60-kDa were detected in extracts of several green algae butnot in extracts of higher plants or a brown alga. ¹This research was partly supported by Grants-in-Aid from theMinistry of Education, Science and Culture, Japan (No. 06454013and 06304023) and Research Fellowship of the Japan Society forthe Promotion of Science for Young Sciencists. ²Research Fellow (PD) of the Japan Society for the Promotionof Science.     

Sodium Stimulates Regeneration of Phosphoenolpyruvate in Mesophyll Chloroplasts of Amaranthus tricolor

Mesophyll chloroplasts were isolated from leaves of a Na⁺-requiringNAD-malic enzyme type, dicotyledonous C₄ plant, Amaranthus tricolorL. The chloroplasts converted pyruvate to phosphoenolpyruvateunder illumination, and the conversion was stimulated by Na⁺.This observation may explain the requirement for Na⁺ of someC₄ plants. ² Present address: Institute for Life Science Research, NihonNohyaku Co., Ltd., Kawachi-Nagano, Osaka, 586 Japan     

Separation and Partial Characterization of Membranes from Prochloron sp.

Two differently colored membrane preparations were separatedfrom the prochlorophyte, Prochloron sp., by mechanical disintegrationof the cells followed by sucrose density gradient centrifugation.An orange-colored preparation, containing zeaxanthin as themajor constituent pigment, seemed to comprise the cytoplasmicmembrane. The other green-colored membrane preparation, containingß-carotene and chlorophyll a and b as major pigmentconstituents, was identified as the thylakoid membrane. Thetwo types of membranes were compared as to their absorptionspectra and buoyant densities. ¹ This work is one of the results of the 8th International Expeditionon Prochloron organized by Dr. R. A. Lewin, University of Californiaat San Diego. ⁵ Present address: Solar Energy Research Group, The Algatron,The Institute of Physical and Chemical Research (RIKEN), Wako-shi,Saitama 351, Japan. ⁶ Present address: National Institute for Basic Biology, Okazaki444, Japan. (Received October 19, 1984; Accepted January 7, 1985)     

Purification of Sulphite-Cytochrome c Reductase of Thiobacillus novellus and Reconstitution of Its Sulphite Oxidase System with the Purified Constituents

Sulphite-cytochrome c reductase (sulphite: ferricytochrome coxidoreductase, EC 1.8.2.1 [EC] ) derived from Thiobacillus novelluswas purified by chromatography on a DEAE-cellulose column andby gel filtration with a Sephadex G-100 column. Although thereductase thus purified moved as a single band both in gel filtrationand in isoelectric focusing it was always split into two bandsby polyacrylamide gel electrophoresis; the one had the enzymaticactivity and showed absorption spectrum of cytochrome, whilethe other had no activity and was colourless, in contrast withthe results reported by Charles and Suzuki [(1966) Biochim.Biophys. Acta 128: 522]. The enzymatic properties of the purifiedreductase were almost the same as those of the enzyme obtainedby Charles and Suzuki. Cytochrome c-551 free of the reductase activity was obtained.Its molecular weight was determined to be 23,000 by polyacrylamidegel electrophoresis in the presence of sodium dodecyl sulphate.The cytochrome seemed to exist in the organism as a complexwith the reductase or a subunit of the enzyme. In the stateof the complex with the enzyme, the cytochrome was reduced veryquickly on addition of sulphite, while the cytochrome free ofthe reductase activity was hardly reduced by the enzyme withsulphite. A sulphite oxidase system was reconstituted with the reductase,cytochrome c-550 and cytochrome oxidase highly purified fromthe bacterium. ¹ Present address: Water Research Institute, Nagoya University,Nagoya 464, Japan ² Present address: Institute for Biological Science, SumitomoChemical Co., Ltd., Takarazuka, Hyogo 665, Japan (Received January 23, 1981; Accepted March 9, 1981)     

Comparative Studies of NAD-Malic Enzyme from Leaves of Various C4 Plants

Using butyl-TSK-gel chromatography, we purified NAD-malic enzyme(ME) (EC 1.1.1.39 [EC] ), which is involved in C₄ photosynthesis,to electrophoretic homogeneity, from leaves of Amaran-thus tricolor.Molecular weights of the native and SDS-denatured enzyme fromA. tricolor were 490 kDa and 61 kDa, respectively. During assayof the enzyme there was a slow reaction transient in the formof a lag before a steady-state rate was reached. The durationof this lag was inversely proportional to the concentrationof each substrate and the activator, fructose- 1,6-bis-phosphate(FBP). The optimal pH of the reaction fell with decreasing concentrationsof either malate or FBP. High pH prolonged the lag in reaction. Double reciprocal plots of the enzymatic activity as a functionof the concentration of malate yielded straight lines and didnot show any cooperativity for binding of malate. The enzymefrom A. tricolor was not inhibited by either HCO^–₃ orCO₂. At different concentrations of malate, the nature of theactivating effect of FBP was compared among the purified enzymesfrom A. tricolor and the C₄ monocots Eleusine coracana and Panicumdichotomiflorum. At low levels of malate, FBP markedly stimulatedthe enzyme from each species. In contrast, at saturating levelsof malate, the response of enzymes to increasing concentrationsof FBP was different and depended on the source of enzyme. The immunochemical properties of the enzymes from the threespecies were compared using an enzyme-linked immunoadsorbentassay with antisera raised against the purified enzymes fromthe three species. Different cross-reactivities were observedamong the enzymes from different sources. The N-terminal aminoacid sequences of NAD-MEs from the three species were determinedand some differences were found among the three enzymes. ²Permanent address; Tohoku National Agricultural ExperimentStation, Morioka, 020-01 Japan. ³Permanent address; National Grassland Research Institute, Nishinasuno,Tochigi, 329-27 Japan. (Received December 12, 1988; Accepted February 17, 1989)     

High Affinity of the 5'-Upstream Region of a Winged Bean Chymotrypsin Inhibitor Gene for Nuclear Matrix

The 5'-upstream region of a winged bean chymotrypsin inhibitorgene (WCI-3b) was found to have a high affinity for nuclearmatrix. The region, named WCI-3b MAR (matrix attachment region),is highly A+T-rich and contains multiple sites interacting withnuclear matrix. A MAR was also found in the corresponding regionof the WCI-x gene, another active gene of the WCI family. SeveralMAR-binding proteins were detected in the wheat nuclear matrix. ⁴Present address: Friedrich Miescher Institute, P.O. Box 2543,CH-4002 Basel, Switzerland. ⁵Present address: Research Institute for Biological Sciences(RIBS), Kayo-cho, Jyobo-gun, Okayama, 716–1241 Japan.     

Odorant responses of Na+-K+ ATPase activity by preparations from paired turbinals of rat olfactory tissue

Nerve ending particle (NEP) fractions were prepared from homogenatesof rat olfactory epithelium by differential centrifugation.Homogenates were made from each of the four turbinals from theright and left sides. Na⁺-K⁺ ATPase activity and its responsein vitro to seven odorous chemicals was measured for each NEPfraction. Each odorous chemical generated a different patternof response of enzyme activity in the eight fractions. Analysisof the results of enzyme activity perturbation indicated thatthe turbinals are not bilaterally symmetric. ¹ Paper #4590, Mississippii Agricultural Experiment Station,Mississippi State, MS 39762. This work was supported by theOffice of Research and Graduate Studies, Mississippi State Universityand Army Research Office Contract #DAAG 29-80-C-0033.     

Distribution of Fallover in the Carboxylase Reaction and Fallover-Inducible Sites among Ribulose 1,5-Bisphosphate Carboxylase/Oxygenases of Photosynthetic Organisms

The biphasic reaction course, fallover, of carboxyla-tion catalysedby ribulose 1,5-bisphosphate carboxylase/ox-ygenase (RuBisCO)has been known as a characteristic of the enzyme from higherland plants. Fallover consists of hysteresis in the reactionseen during the initial several minutes and a very slow suicideinhibition by inhibitors formed from the substrate ribulose-l,5-bisphosphate(RuBP). This study examined the relationship between occurrenceof fallover and non-catalytic RuBP-binding sites, and the putativehysteresis-inducible sites (Lys-21 and Lys-30S of the largesubunit in spinach RuBisCO) amongst RuBisCOs of a wide varietyof photosynthetic organisms. Fallover could be detected by followingthe course of the carboxylase reaction at 1 mM RuBP and thenon-catalytic binding sites by alleviation of fallover at 5mM RuBP. RuBisCO from Euglena gracilis showed the same linearreaction course at both RuBP concentrations, indicating an associationbetween an absence of fallover and an absence of the non-catalyticbinding sites. This was supported by the results of an equilibriumbinding assay for this enzyme with a transition state analogue.Green macroalgae and non-green algae contained the plant-type,fallover enzyme. RuBisCOs from Conjugatae, Closterium ehrenbergii,Gona-tozygon monotaenium and Netrium digitus, showed a muchsmaller decrease in activity at 1 mM RuBP than the spinach enzymeand the reaction courses of these enzymes at 5 mM RuBP werealmost linear. RuBisCO of a primitive type Conjugatae, Mesotaeniumcaldariorum, showed the same linear course at both RuBP concentrations.Sequencing of rbcL of these organisms indicated that Lys-305was changed into arginine with Lys-21 conserved. ⁷ On leave from Research and Development Center, Unitika Ltd.,23 Kozakura, Uji, Kyoto, 611 Japan. ⁸ Present address: Department of Applied Biological Chemistry,Faculty of Agriculture, Tohoku University, Tsutsumidori-Ama-miyamachi, Sendai, 981 Japan. ⁹ Present address: National Institute for Basic Biology, Myodaiji,Okazaki, 444 Japan. ¹⁰ Present address: Department of Environmental Biology, TokyoPharmaceutical University, Hachioji, Tokyo, 192-03 Japan.     

Properties of S-adenosyl-L-methionine-magnesium-protoporphyrin IX methyltransferase from barley

S-Adenosyl-L-methionine-magnesium-protoporphyrin IX methyltransferase(EC 2.1.1.11 [EC] ) is present in greening barley seedlings associatedwith the particulate fraction. This enzyme was purified 20 foldusing protamine and ammonium sulfate precipitation. The enzymewas active over a wide pH range with highest activity at pH7.5. The Km values for Mg-protoporphyrin IX and S-adenosylmethioninewere 48 and 39 µM, respectively; S-adenosylethionine andS-adenosyihomocysteine were competitive inhibitors with respectto S-adenosylmethionine; hemin inhibition was non-competitivewith respect to Mg-protoporphyrin IX; thiol compounds exhibiteda stimulatory effect on enzyme activity. The properties of theenzyme are discussed and compared with the enzyme from otherorganisms. ¹ This research was supported in part by the Utah State AgriculturalExperiment Station. ² Present address: Department of Chemistry, Boston University,Boston, Massachusetts, U. S. A. ³ Present address: Department of Biochemistry and Microbiology,Faculty of Pharmacy, Comenius University, Bratislava, Czechoslovakia. (Received February 20, 1978; )     

Immunocytochemical Localization of Uricase in Peroxisomes of Soybean Cotyledons

Antibodies specific for nodule uricase were used for immunocytochemistryto demonstrate the presence of uricase in cotyledons of soybean(Glycine max) during germination and early seedling growth.The enzyme was localized exclusively in peroxisomes. ¹Permanent address: Department of Plant Cytology and Cytochemistry,University of Lodz, Lodz, Poland ²Current address: Department of Plant Science, University ofArizona, Tucson, AZ 85721, U.S.A.     

Malate Decarboxylation by Mitochondria of the Inducible Crassulacean Acid Metabolism Plant Mesembryanthemum crystallinum

Mitochondria isolated from leaves of Mesembryanthemum crystallinumoxidized malate by both NAD malic enzyme and NAD malate dehydrogenase.Rates of malate oxidation were higher in mitochondria from plantsgrown at 400 mil NaCl in the rooting medium and performing Crassulaceanacid metabolism (CAM) than in mitochondria from plants grownat 20 mM NaCl and exhibiting C₃-photosynthetic CO₂ fixation.The mitochondria isolated from plants both in the CAM and C₃modes were tightly coupled and gave high respiratory control.At optimum pH for malate oxidation (pH 7.0), pyruvate was themajor product in mitochondria from CAM-M. crystallinum, whereasmitochondria from C₃-M. crystallinum produced predominantlyoxaloacetate. Both the extracted NAD malic enzyme in the presenceof CoA and the oxidation of malate to pyruvate by the mitochondriafrom plants in the CAM mode had a pH optimum around 7.0 withactivity declining markedly above this pH. The activity of NAD-malicenzyme, expressed on a cytochrome c oxidase activity basis,was much higher in mitochondria from the CAM mode than the C₃mode. The results indicate that mitochondria of this speciesare adapted to decarboxylate malate at high rates during CAM. ¹Current address: Lehrstuhl für Botanik II, UniversitätWurzburg, Mittlerer Dallenbergweg 64, 8700 Würzburg, WestGermany. ²Current address: KD 120, Chemical Research Division, OntarioHydro, 800 Kipling Avenue, Toronto, Ontario M8Z5S4, Canada. ³Current address: Department of Botany, Washington State University,Pullman, Washington 99164-4230, U.S.A. (Received March 13, 1986; Accepted September 18, 1986)     

Citrate metabolism in. soybean cotyledons

Citrate metabolism and the citrate cleavage enzyme were investigatedin soybean (Glycine max (L.), Merr.) cotyledons throughout developmentand during the first 5 days of germination. It was noted thatboth the lipid synthesizing and the acetyl CoA generating systemsare present when the soybean seed matures, and that the activityof these systems declines throughout development as citrateincreases. Citrate represents 1% of the cotyledon dry weightat seed maturity. During the first 24 hr of germination, therewas an activation of the citrate cleavage enzyme and a concomitantdrop of some 60% in citrate content. Accompanying the drop incitrate content is the de novo synthesis of fatty acids foruse in the production of phospholipids. All of the data areconsistent with the hypothesis that acetyl CoA for lipid synthesisis supplied by the citrate molecule via the citrate cleavageenzyme and that activity of this system is necessary both duringseed development and during germination. ¹ Research was supported by cooperative investigations of theAgricultural Research Service, United States Department of Agriculture,and Illinois Agricultural Experiment Station. ² This research represents partial fulfillment of Ph.D. degree. (Received September 20, 1976; )     

Molecular Cloning and Characterization of S-Adenosyl-L-Methionine:Scoulerine-9-O-Methyltransferase from Cultured Cells of Coptis japonica

S-Adenosyl-L-methionine : scoulerine-9-O-methyltransferase (SMT)catalyzes the transfer of the S-methyl group of S-adenosyl-L-methionineto the 9-hydroxyl group of scoulerine during the biosynthesisof berberine. We have isolated functionally active cDNA clones(pCJSMTs) from a cDNA library prepared from cultured cells ofCoptis japonica. The longest cDNA insert (pCJSMT1) had an openreading frame that encoded 351 amino acids, but the calculatedmolecular mass (38,364 Da) of the deduced product was slightlylower than the experimentally determined molecular mass of purifiedSMT. Rapid amplification of the 5' end of the cDNA indicatedthat the full-length cDNA of SMT consisted of 1,458 nucleotidesthat encoded 381 amino acids. When the full-length cDNA wasexpressed in E. coli, the molecular mass of the expressed SMTwas greater than that of native SMT in Coptis cells. This resultsuggests that SMT might be produced in a pre-mature form andprocessed post-translationally. SMT was also found to exhibitsequence homology to other O-methyltransferases from plantsand N-terminal region of the SMT polypeptide appeared to benecessary for enzymatic activity. ¹Present address: High Quality Life Research Laboratories, SumitomoMetal Industries, Ltd., 3-5 Hikaridai, Seika, Sourakugun, Kyoto,619-02 Japan ²Present address: Suntory Research Center, 1-1-1 Wakayamadai,Shimamoto, Mishima-gun, Osaka, 618 Japan ³Present address: Department of Cell Biology, The Scripps ResearchInstitute, La Jolla, CA 92037 U.S.A.     

The presence of gibberellin A20 in Stevia rebaudiana and its significance for the biological activity of steviol

Gibberellin-like substances of stems and leaves from Steviarebaudiana were analyzed and gibberellin A₂₀ was identifiedby gas chromatography-mass spectrometry. The presence of GA₂₀in S. rebaudiana is significant for the interpretation of thegibberellin activity of steviol. It indicates that steviol,the C-13 hydroxykaurenoic acid, may function as a precursorfor C-13 hydroxy-gibberellins and not as a gibberellin analog. ¹ This work was supported by National Science Foundation GrantGB 17304 to M. R. and by a Research Grant-in-Aid from SigmaXi to L. M. A. The research described is from a dissertationsubmitted by L. M. A. in partial fulfillment of the requirementsfor the Ph.D. degree. ² Present address: Laboratory of Plant Morphogenesis, Departmentof Biology, Manhattan College, Bronx, N. Y. 10471, U. S. A. (Received June 12, 1978; )     

Involvement of Calcium in Adventitious Bud Initiation in Torenia Stem Segments

In Torenia stem segments cultured in vitro, active meristematicdivisions are induced in the epidermis by treatment with cytokinin,resulting in the formation of adventitious buds. Applicationof the calcium ionophore A23187 [GenBank] was found to induce meristematicdivisions in the absence of cytokinin. The induction by A23187 [GenBank] was inhibited by simultaneous addition of auxin, but not byanti-cytokinin. A two hour pre-treatment with A23187 [GenBank] was alsoeffective, but only when it was applied to the explants justafter their excision from mother plants. The A23187 [GenBank] -inducedmeristematic zones developed into dome-shaped structures, butnot into complete adventitious buds. Complete elimination ofcalcium from the culture medium caused 50% inhibition of A23187 [GenBank] -and/or cytokinin-induced initiation of meristematic divisions.When the explants were preincubated with EGTA and then culturedon a Ca-free medium containing EGTA, cytokinin failed to inducebud initiation. Similar inhibition was also obtained by lanthanum,a calcium antagonist, by verapamil, a calcium channel inhibitor,and by trifluoperazine and chlorpromazine, calmodulin inhibitors.These results support the idea that adventitious bud initiationinduced by cytokinin in Torenia stem segments may be mediated,at least partially, by an increase in the level of intracellularCa²⁺. ¹Bioscience Research Center, Mitsui Petrochemical IndustriesLtd., Waki-cho, Kuga-gun, Yamaguchi 740, Japan. (Received May 9, 1985; Accepted October 5, 1985)