Organization of transport from endoplasmic reticulum to Golgi in higher plants

In plant cells, the organization of the Golgi apparatus and its interrelationships with the endoplasmic reticulum differ from those in mammalian and yeast cells. Endoplasmic reticulum and Golgi apparatus can now be visualized in plant cells in vivo with green fluorescent protein (GFP) specifically directed to these compartments. This makes it possible to study the dynamics of the membrane transport between these two organelles in the living cells. The GFP approach, in conjunction with a considerable volume of data about proteins participating in the transport between endoplasmic reticulum and Golgi in yeast and mammalian cells and the identification of their putative plant homologues, should allow the establishment of an experimental model in which to test the involvement of the candidate proteins in plants. As a first step towards the development of such a system, we are using Sar1, a small G-protein necessary for vesicle budding from the endoplasmic reticulum. This work has demonstrated that the introduction of Sar1 mutants blocks the transport from endoplasmic reticulum to Golgi in vivo in tobacco leaf epidermal cells and has therefore confirmed the feasibility of this approach to test the function of other proteins that are presumably involved in this step of endomembrane trafficking in plant cells.

Temperament and personality: origins and outcomes

This article reviews how a temperament approach emphasizing biological and developmental processes can integrate constructs from subdisciplines of psychology to further the study of personality. Basic measurement strategies and findings in the investigation of temperament in infancy and childhood are reviewed. These include linkage of temperament dimensions with basic affective-motivational and attentional systems, including positive affect/approach, fear, frustration/anger, and effortful control. Contributions of biological models that may support these processes are then reviewed. Research indicating how a temperament approach can lead researchers of social and personality development to investigate important person-environment interactions is also discussed. Lastly, adult research suggesting links between temperament dispositions and the Big Five personality factors is described.

Organization of transport from endoplasmic reticulum to Golgi in higher plants

In plant cells, the organization of the Golgi apparatus and its interrelationships with the endoplasmic reticulum differ from those in mammalian and yeast cells. Endoplasmic reticulum and Golgi apparatus can now be visualized in plant cells in vivo with green fluorescent protein (GFP) specifically directed to these compartments. This makes it possible to study the dynamics of the membrane transport between these two organelles in the living cells. The GFP approach, in conjunction with a considerable volume of data about proteins participating in the transport between endoplasmic reticulum and Golgi in yeast and mammalian cells and the identification of their putative plant homologues, should allow the establishment of an experimental model in which to test the involvement of the candidate proteins in plants. As a first step towards the development of such a system, we are using Sar1, a small G-protein necessary for vesicle budding from the endoplasmic reticulum. This work has demonstrated that the introduction of Sar1 mutants blocks the transport from endoplasmic reticulum to Golgi in vivo in tobacco leaf epidermal cells and has therefore confirmed the feasibility of this approach to test the function of other proteins that are presumably involved in this step of endomembrane trafficking in plant cells.

Proteins involved in membrane transport between the ER and the Golgi apparatus: 21 putative plant homologues revealed by dbEST searching

Numerous proteins have been identified in yeast and mammalian cells which are involved in trafficking between the endoplasmic reticulum and the Golgi apparatus. A great number of partial cDNA sequences now available from the two major plant model species, Arabidopsis thaliana and Oryza sativa, makes it possible to identify putative plant homologues of known genes/proteins from non-plant species. The authors used this approach to screen the database of Expressed Sequence Tags (dbEST) in order to detect plant homologues of proteins involved in membrane transport between ER and Golgi. Availability of these partial sequences will facilitate the screening of cDNA and genomic libraries otherwise performed using heterologous probes derived from animal and yeast genes. As the plant Golgi complex differs in many respects from its mammalian and yeast counterparts, the dbEST clones found can be directly used for various functional assays (immunoprecipitation, two-hybrid analysis, transgenic plants etc.) to test the exact roles of the encoded proteins and identify their functional partners, some of which may be specific for plants.

Expression and characterization of PP7, a novel plant protein Ser/Thr phosphatase distantly related to RdgC/PPEF and PP5

We have recently identified an Arabidopsis thaliana cDNA encoding a putative protein Ser/Thr phosphatase PP7, not closely related to any protein phosphatases in animals or fungi. Here, we describe the characterization of PP7 expressed in a bacterial system. The recombinant protein was inactive unless the longest insert in its catalytic domain was cleaved, suggesting that this insert is an autoinhibitory region. PP7 was resistant to okadaic acid, calyculin and fumonisin B1, and was stimulated by Mn2+ or Fe2+, while Ni2+ and Zn2+ were inhibitory. Polylysine stimulated PP7 activity towards p-nitrophenylphosphate but inhibited activity towards the most efficient protein substrate, myelin basic protein. A tentative model of the control of PP7 activity is proposed.

A calcium pump at the higher plant nuclear envelope?

Evidence for a Ca2+-pump at the nuclear envelope (NE) in plant cells has been obtained using confocal and electron microscope immunocytochemistry and antibodies raised to a plant homologue of the mammalian SERCA pump. This is the first evidence suggesting an NE Ca2+-pump in plants. In addition to being localised with the NE in interphase, the antigen was localised to membrane derived from the NE and associated ER during mitosis, correlating with known Ca2+-pools. The work suggests that a SERCA pump is present at the NE of plant as well as animal cells.

PP7, a plant phosphatase representing a novel evolutionary branch of eukaryotic protein Ser/Thr phosphatases

We describe a novel protein Ser/Thr phosphatase from Arabidopsis thaliana, PP7, which is only 27-32% identical in amino acid sequence to the known phosphatases and is the most divergent member of the PPP (PP1/2A/2B) family for today. Some structural features suggest more close relationship of PP7 to the PP5/rdgC subfamily. PP7 contains all of the residues essential for the phosphatase activity and possesses three major insertions in its presumable C-terminal subdomain, which suggest its unique regulation and/or optimisation of its structure for interaction with specific substrates or regulators. A phosphatase structurally related to PP7 is expressed in rice. PP7 conservation between mono- and dicotyledonous plants may point to its essential role in the plant cell.

Expression of nitric oxide synthase isoforms in bone and bone cell cultures

Recent work has shown that nitric oxide (NO) acts as an important mediator of the effects of proinflammatory cytokines and mechanical strain in bone. Although several bone-derived cells have been shown to produce NO in vitro, less is known about the isoforms of NO synthase (NOS), which are expressed in bone or their cellular distribution. Here we investigated the expression, cellular localization, and regulation of NOS mRNA and protein in cultured bone-derived cells and in bone tissue sections. We failed to detect inducible NOS (iNOS) protein in normal bone using immunohistochemical techniques, even though low levels of iNOS mRNA were detected by sensitive reverse transcribed polymerase chain reaction (RT-PCR) assays in RNA extracted from whole bone samples. Cytokine stimulation of bone-derived cells and bone explant cultures caused dramatic induction of iNOS mRNA and protein in osteoblasts and bone marrow macrophages, but no evidence of iNOS expression was seen in osteoclasts by immunohistochemistry or in situ hybridization. Endothelial NOS (ecNOS) mRNA was also detected by RT-PCR in whole bone, and immunohistochemical studies showed widespread ecNOS expression in bone marrow cells and trabecular lining cells in vivo. Related studies in vitro confirmed that ecNOS was expressed in cultured osteoblasts, stromal cells, and osteoclasts. Neuronal NOS mRNA was detected by RT-PCR in whole bone, but we were unable to detect nNOS protein in bone cells in vivo or in studies of cultured bone-derived cells in vitro. In summary, our data show that mRNAs for all three NOS isoforms are expressed in bone and provide evidence for differential expression and regulation of the enzymes in different cell types. These findings confirm the likely importance of the L-arginine-NO pathway as a physiological mediator of bone cell function and demonstrate that it may be possible to exert differential effects on osteoblast and osteoclast activity in vivo by differential targeting of constitutive and inducible NOS isoforms by selective NOS inhibitors.

[Genes of plant Ser/Thr protein phosphatases: detection of sequences related to PPT/rdgC]

An unknown sequence that may encode a fragment of the Ser/Thr protein phosphatase (designated PP6Zm) related to PPT/rdgC phosphatases was identified using PCR on maize genomic DNA. A dbEST search using a partial amino acid sequence of PP6Zm revealed a putative homolog of PP6Zm expressed in Arabidopsis thaliana (EMBL AT6726). A search of the SwissProt database indicated that the partial amino acid sequence of AT6726 has the highest identity (54.3%) to the rdgC phosphatase from Drosophila melanogaster. The maize phosphatase PP1Zm6, described previously as a PP1 isoform (EMBO J., 1993, vol. 12, p. 3497), was found by us to be plant homolog of mammalian PPT. In addition, six fragments of new (pseudo) genes homologous to the phosphatase genes encoding PP1, PP2A, and PPX isoforms were detected in the maize genome. The existence in maize of a multigene PP2A family, reported only for dicotyledons, and of a PP1 multigene family, found earlier in both di- and monocotyledons, was shown.

Visualization of Golgi apparatus in methacrylate embedded conifer embryo tissue using the monoclonal antibody JIM 84

Methacrylate embedding followed by resin removal has been used for the first time to visualize a membrane-associated antigen at the tissue level. Monoclonal antibody JIM 84 was used to stain the Golgi apparatus of gymnosperm (conifer) embryos by light microscope immunocytochemistry. Specificity of labelling was confirmed by electron microscope immunocytochemistry using LR-white resin. GA staining was evident in all stages of white spruce somatic embryo development from immature to mature. Some regions of the somatic embryos (e.g. root cap/suspensor region) stained more vigorously than other regions (hypocotyl/cotyledon end). GA also stained in roots of Monterey pine and Douglas fir. Unlike the situation in most angiosperms, JIM 84 antigen appears to be absent from the conifer plasma membrane. However, it appears to be present in representatives of both major classes of higher plants.

[Cloning and expression of cDNA for tobacco rab1, and structural-functional analysis of the protein]

rab1 cDNA coding for a small GTP binding protein Rab1 was isolated from cDNA library of tobacco (Nicotiana tabacum) leaves. The primary structure of this protein was deduced from the rab1 structure. Tobacco rab1 cDNA was expressed in Escherichia coli, and the product was purified and shown to exhibit GTPase activity. A set of Rab1 mutants with altered GTP binding and/or GTPase activities was obtained. Polyclonal antipeptide antibodies were raised against a sequence in the C-terminal region of the tobacco Rab1 capable of recognizing this protein.

Genomic sequence of a calnexin homolog from Arabidopsis thaliana

Calnexin is a membrane-bound protein of the ER in animal cells (Wada et al., 1991). It shows considerable similarity to the major calcium-sequestering protein of the ER lumen, calreticulin, with two calcium-binding regions--a high-affinity, low-capacity region in the ER lumen and a low-affinity, high-capacity region in the cytoplasm. The protein is postulated to act as a calcium-regulated chaperone during protein maturation (Ou et al., 1993). We have isolated a genomic sequence showing significant homology to the animal gene over the predicted coding sequence (Table I). A partial cDNA from Zea mays was isolated from an expression library made from 6-d coleoptiles (Clontech, Palo Alto, CA). The library was screened using a monoclonal antibody raised against a small number of microsomal proteins resulting from a partial purification of plasma membrane Ca2+ ATPase (Briars et al., 1988). The partial cDNA showed sequence homology to the calcium-binding region common to calreticulin and calnexin. The fragment was used to screen a genomic library constructed from Arabidopsis thaliana (cv Larasbonerecta), and a 15-kb fragment was isolated and subcloned and the relevant subfragments were sequenced. The coding region contains five introns, two in the N-terminal region and three in the C-terminal region. The predicted amino acid sequence shows a high level of homology with the animal calnexin, although the terminal highly acidic calcium-binding region is shorter. A cDNA for a putative homolog of calnexin was isolated from A. thaliana (cv Columbia) by Huang et al.(1993); our coding sequence shows 85% identity and 92% similarity determined by FASTA (Wisconsin Genetics Computer Group package); however, the differences are greater than would be expected between cultivars of the same species. A Southern blot probed with DNA from the central calcium-binding region shows multiple bands. This, combined with the sequence heterogeneity, suggests that calnexin belongs to a family of related genes.

PM-type calcium pumps are associated with higher plant cell intracellular membranes

The supposition that all eukaryotic cell types contain a plasma membrane (PM)-type Ca pump (i.e. a Ca pump which is directly-stimulated by calmodulin and located exclusively at the PM) has been questioned by recent data from higher plant cells. These studies suggest the presence of Ca pumps directly stimulated by calmodulin associated with an intracellular membrane (probably the endoplasmic reticulum, ER) in a variety of monocotelydonous and dicotelydonous species. Thus plants have a 'PM-type' Ca pump at an intracellular membrane. The evidence for this includes studies on isolated membranes, purification and functional reconstitution and phosphorylated intermediate formation. Plant cells also contain a homologue of the sarcoplasmic reticulum/endoplasmic reticulum (SR/ER) Ca pump, probably located at the ER. The implications of these new data for our appreciation of the structure, function and location of eukaryotic Ca pumps are discussed, together with recent data from the use of inhibitors specific to mammalian ER/SR Ca pumps.

A comparison between mivacurium and suxamethonium in children

The neuromuscular effects of mivacurium were compared with those of suxamethonium in 69 children (aged 2-12 years), during nitrous oxide, oxygen and halothane anaesthesia in a randomised open study. Neuromuscular block was monitored by measuring the acceleration of the thumb caused by contraction of the adductor pollicis muscle after supramaximal stimulation of the ulnar nerve at the wrist using an Accelograph. End-tidal carbon dioxide was maintained at about 4 kPa in both groups. The mean times (95% confidence intervals) for T1:T0 ratio to decrease to 75%, 50%, 25% and 5% of control values were 50 (42-59), 62 (52-74), 83 (68-100) and 93 (46-108) s respectively for mivacurium and 18 (15-22), 26 (22-30), 32 (28-37) and 43 (38-49) s respectively for suxamethonium. The times for T1:T0 ratio to recover to 25%, 50% and 70% of control values were 615 (542-698), 769 (687-859) and 901 (820-993) s respectively for mivacurium and 196 (179-214), 216 (201-234) and 242 (216-259) s respectively for suxamethonium. The range of maximum block was similar for both drugs. The average time to reach maximum block was 143 s for mivacurium and 56 s for suxamethonium. Intubating conditions were similar in the two groups.

Reconstitution and Characterization of a Calmodulin-Stimulated Ca-Pumping ATPase Purified from Brassica oleracea L

Purification and functional reconstitution of a calmodulin-stimulated Ca(2+)-ATPase from cauliflower (Brassica oleracea L.) is described. Activity was purified about 120-fold from a microsomal fraction using calmodulin-affinity chromatography. The purified fraction showed a polypeptide at 115 kD, which formed a phosphorylated intermediate in the presence of Ca(2+), together with a few polypeptides with lower molecular masses that were not phosphorylated. The ATPase was reconstituted into liposomes by 3-([cholamidopropyl]-dimethylammonio-)1-propanesulfonate (CHAPS) dialysis. The proteoliposomes showed ATP-dependent Ca(2+) uptake and ATPase activity, both of which were stimulated about 4-fold by calmodulin. Specific ATPase activity was about 5 mumol min(-1) (mg protein)(-1), and the Ca(2+)/ATP ratio was 0.1 to 0.5 when the ATPase was reconstituted with entrapped oxalate. The purified, reconstituted Ca(2+)-ATPase was inhibited by vanadate and erythrosin B, but not by cyclopiazonic acid and thapsigargin. Activity was supported by ATP (100%) and GTP (50%) and had a pH optimum of about 7.0. The effect of monovalent and divalent cations (including Ca(2+)) on activity is described. Assay of membranes purified by two-phase partitioning indicated that approximately 95% of the activity was associated with intracellular membranes, but only about 5% with plasma membranes. Sucrose gradient centrifugation suggests that the endoplasmic reticulum is the major cellular location of calmodulin-stimulated Ca(2+)-pumping ATPase in Brassica oleracea inflorescences.

The interrelationship between the accumulation of lipids, protein and the level of acyl carrier protein during the development of Brassica napus L. pollen

Lipid accumulation during pollen and tapetal development was studied using cryostat sections of unfixed anthers from Brassica napus (rapeseed). Diamidino-2-henylindole (DAPI), a DNA fluorochrome, was used to stain the pollen nuclei in order to identify ten stages of pollen development in Brassica. Storage lipids (i.e. triacylglycerides) were stained using the fluorochrome Nile red. Pollen coat lipids are formed in tapetal plastids between the mid-vacuolate and early maturation pollen stages. The pollen coat components, including lipids and a proportion of the proteins, are derived from the remnants of the tapetum, after its rupture, during the second pollen mitosis. Quantitative microfluorometric analyses demonstrated four phases of lipid body accumulation or depletion in the developing pollen cytoplasm. The majority of storage lipids found in the cytoplasm of the mature pollen grain accumulated during the late vacuolate and early maturation stages when the pollen is bicellular. The level of acyl carrier protein, a protein integrally involved in lipid synthesis, was also found to be maximal in the developing pollen during the bicellular pollen stages of development. This coincided with the most active period of lipid accumulation. These data could indicate that the lipids of the pollen are synthesized in situ, by metabolic processes regulated by expression of genes in the haploid genome.

A method for bioassay of potency and effectiveness of inhaled bronchodilators in normal subjects

1. Bioassay of inhaled bronchodilator drugs for potency and effectiveness in normal human subjects is rendered difficult and imprecise because bronchomotor tone is low. When attempting to determine log dose-effect relationships for inhaled, nebulised bronchodilator drugs and measuring increased specific airways conductance (sGaw), the coefficient of variation of each mean response is likely to be so large that an intermediate response is not significantly different from either the maximum or no response. 2. A method is described by which inhaled, nebulised bronchodilator drugs can be bioassayed for potency and effectiveness with high precision. The method involves the use of inhaled, nebulised bronchoconstrictor agents (methacholine or histamine) to provide a highly reproducible, near-constant, background reduction in airway conductance in normal human subjects. The activity of bronchodilators is assessed against this background reduction in airway conductance. 3. Log specific airway conductance (log sGaw) was chosen as the response metameter on grounds of normality of distribution and relative homoscedasticity. A central straight line segment of the bronchoconstrictor drug dose-effect curve extending over a 10-fold dose multiple could be found easily; the upper end of this segment occurred near 67-75% reduction in sGaw and was reproducible. 4. The effect of a dose bronchoconstrictor drug causing 67-75% reduction in sGaw waned linearly with time at first, over the effect segment corresponding to the linear segment of the drug's log dose-effect curve. The rate constant of local elimination of bronchoconstrictor drug from its site of action, in inhaled dose equivalents, was deduced from the ratio of the slopes of the linear segments of the log dose-effect and time-effect curves. 5. The maintenance dose rate to maintain the peak effect (67-75% reduction in sGaw) of the loading dose was calculated. The repeated administration of maintenance doses at regular short intervals, at this calculated dose rate, created a steady state of bronchoconstriction equal in extent to the effect of the loading dose. This steady state bronchoconstriction occurred without undue discomfort for the subject and was reproducible. 6. Against this background bronchoconstriction, inhaled, nebulised salbutamol produced a rapidly developing and slowly waning increase in sGaw. Reproducible log dose-effect curves for the bronchodilator drugs salbutamol and reproterol allowed measurement of their potency and effectiveness; the potency of reproterol relative to salbutamol was 0.082 with 95% confidence limits of 0.0504 and 0.131. 7. Estimation of the subject's pharmacodynamic and pharmacokinetic parameters for inhaled methacholine from just three dosage individualising sessions provides estimates accurate enough to be of practical value.

Treatment of experimental cerebral air embolism with lidocaine and hyperbaric oxygen

Experiments were performed to assess the combined therapeutic effects of hyperbaric oxygen (HBO) and i.v. lidocaine on neural function after ischemia induced by cerebral air embolism in anesthetized cats. Neural function was determined by measuring the somatosensory evoked potential (SEP) amplitude. Air was infused into the carotid artery in increments of 0.08 ml to maintain the SEP amplitude at 10% or less of baseline values for 15 min. Three groups were studied. A control group (n = 9) received no further treatment after SEP suppression. An HBO group (n = 8) was treated with oxygen at 2.8 atm abs for 130 min. A third group (n = 8) received an i.v. lidocaine infusion in addition to HBO. Air infusion suppressed the SEP amplitude to the same level in all groups. The control group recovered 27.4 +/- 5.5% (mean +/- SEM) of the baseline SEP amplitude, whereas the HBO group recovered 62.0% +/- 7.2%, and the HBO plus lidocaine group recovered 75.3 +/- 5.7%. The results show that both HBO and the combination of HBO and lidocaine promote a significant recovery of the SEP amplitude compared to no treatment. However, lidocaine therapy adds no benefit to HBO therapy alone.

Surface hydrophobicity and dispersal of Pseudomonas aeruginosa from biofilms

A novel method of cell culture was employed to control the growth-rate of bacterial biofilms [1]. Cell-surface hydrophobicity increased progressively with growth rate for planktonic, chemostatgrown Pseudomonas aeruginosa and also for cells, resuspended from the biofilms. Dependence of surface hydrophobicity upon growth rate was greater for the planktonic cells. Newly-formed daughter cells, shed from the biofilms, were in all cases more hydrophilic than their adherent counterparts and demonstrated only slight growth rate dependency for this property.

A Study of Phospholipids and Galactolipids in Pollen of Two Lines of Brassica napus L. (Rapeseed) with Different Ratios of Linoleic to Linolenic Acid

The phospholipids and galactolipids of the pollen-coat and internal domains of two lines of Brassica napus, Wesroona and IXLIN, with different linoleic/linolenic acid ratios (18:2/18:3) have been characterized by normal phase silica high performance liquid chromatography and gas liquid chromatography. The polar lipids of the pollen-coat are similar to leaf lipids in the high proportion of galactolipids (almost 50%) and the fatty acids; 18:3, palmitic (16:0) and hexadecatrienoic (16:3). In contrast, the pollen internal domain, although rich in 18:3, 18:2 and 16:0, is composed primarily of phosphatidyl-choline, -ethanolamine, and -inositol whose 18:2/18:3 ratio is correlated with that of the seed generation. The difference between the two divergent 18:2/18:3 ratio lines is most evident in the internal domain phospholipids. The 18:2/18:3 ratio of the galactolipids of both pollen domains is not significantly effected by the line genotype. The results are interpreted in terms of the previously described ;prokaryotic' and ;eukaryotic' plant desaturation pathways (PG Roughan, CR Slack [1982] Annu Rev Plant Physiol 33: 97-132). We propose that the eukaryotic pathway is the major desaturation pathway providing polyunsaturated fatty acids to the haploid-specified internal domain in which the IXLIN genotype modifies the activity of the sn-2 linoleoyl phosphatidylcholine desaturase/s of the endoplasmic reticulum. In the diploid-specified pollen-coat, our evidence suggests that a combination of the prokaryotic and eukaryotic pathways contribute polyunsaturated fatty acids.

Multiple-channel stimulation of the cochlear nucleus

To further test the feasibility of a central nervous system auditory prosthesis, the characteristics of the electrically evoked middle latency response were studied in a series of acutely anesthetized pigmented guinea pigs, with multi-channel penetrating cochlear nucleus electrodes placed into the cochlear nucleus under direct visualization. These stimulating electrodes consisted of a silicone substrate, with five stimulating pads each, sputtered with iridium. Monopolar and bipolar stimulation were used. Threshold, latency, and input-output functions of the electrically evoked middle latency response were studied. Systematic differences were observed, depending on the site and parameters of stimulation. Principally, higher currents were required to produce waves of equal amplitude when the electrodes were closely spaced. For near electrode pairs, the maximum wave amplitudies obtainable within the limits of tissue safety were much lower than for distant electrode pairs. The slope of the growth function curve was steeper for widely spaced electrodes than for adjacent sites. Monopolar stimulation demonstrated maximum wave amplitudes with the lowest current intensity, implying current spread to the entire cochlear nucleus with this stimulation montage. In some cases, threshold differences were observed, higher thresholds being associated with closely spaced electrodes. These findings are consistent with simple models of the electric fields expected to be generated by these electrode arrays. The results support the hypothesis that activation of subpopulations of auditory brainstem neurons with multi-channel penetrating microelectrodes is possible.

The calmodulin-stimulated ATPase of maize coleoptiles forms a phosphorylated intermediate

The calmodulin-stimulated ATPase of maize coleoptiles is a 140,000 Mr polypeptide. In the present study, formation of a phosphorylated intermediate by the enzyme is demonstrated. Phosphorylation is sensitive to chasing with unlabelled ATP and to hydroxylamine; lanthanum enhances its intensity while calmodulin enhances phosphorylation in the presence of lanthanum but not in its absence. Ethyleneglycol-bis-(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) inhibits phosphorylation of the purified enzyme, but microsome preparations give a band of phosphorylation of 153,000 Mr in its presence. This latter phosphorylated band was not abolished after a variety of permeabilising treatments in the presence of Triton X-100; phosphorylation of the enzyme was absent when sodium deoxycholate was used as the solubilising detergent. The identity of the 153,000 Mr band is discussed.