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PubMed1982

Glucose transport in Streptococcus salivarius. Evidence for the presence of a distinct phosphoenolpyruvate: glucose phosphotransferase system which catalyses the phosphorylation of alpha-methyl glucoside.

A spontaneous mutant of Streptococcus salivarius ATCC 25975 was isolated by inoculating an agar medium containing 11 mM lactose and 0.5 mM 2-deoxyglucose. This mutant grew poorly on 5 mM glucose but almost as well as the parental strain on 110 mM glucose. Uptake of 2-deoxyglucose was abolished by the mutation, and phosphoenolpyruvate: glucose phosphotransferase activity could not be detected with toluenized cells under normal conditions when the glucose concentration was below 5 mM. Data from growth experiments, glycolysis, and uptake studies indicated the presence of a second phosphoenolpyruvate: glucose phosphotransferase system that could catalyze the phosphorylation of alpha-methyl glucoside. The activity of this system was detected by a spectrophotometric assay coupled with lactate dehydrogenase and by a radioactive isotope method using methyl alpha-D-[U-14C] glucoside. The phosphorylation was phosphoenolpyruvate dependent. The apparent Km of the system for glucose and alpha-methyl glucoside was approximately 20 mM. Studies with energy poisons ruled out the possibility of an active transport system, and accumulation of alpha-methyl glucoside argued against facilitated diffusion. It was concluded that the other glucose transport system which allowed growth of the mutant strain of S. salivarius was a second phosphoenolpyruvate: glucose phosphotransferase system.

Biological Transport↗

PubMed1999

Aminoglycoside resistance mediated by the bifunctional enzyme 6'-N-aminoglycoside acetyltransferase-2"-O-aminoglycoside phosphotransferase.

The expression of the bifunctional aminoglycoside inactivating enzyme 6'-N-aminoglycoside acetyltransferase-2"-O-aminoglycoside phosphotransferase is the most important mechanism of high-level aminoglycoside resistance in Staphylococcus and Enterococcus. The enzyme is unique because it presents two different aminoglycoside-modifying activities located in different regions of the molecule. The gene aac(6')-aph(2") which encodes the synthesis of the enzyme is present in Tn4100-like transposons which are inserted both in R plasmids and the chromosomes of aminoglycoside-resistant isolates. The genetic structure of aac(6')-aph(2")-containing isolates indicates that their origin is not clonal, but plasmid conjugation together with multiple insertion events are in the basis of the rapid spread of aminoglycoside resistance among Gram-positive bacteria. There is not any prevalent genetic linkage of aac(6')-aph(2") with other antibiotic-resistance determinant. However, most methicillin resistant Staphylococcus strains present also high-level aminoglycoside resistance as the consequence of constant antibiotic pressure. This situation could change in the next future with the reported reemergence of gentamicin-susceptible MRSA isolates. Recent data show that inhibitors of eukaryotic protein kinases inhibit as well the aminoglycoside phosphotransferase activity. This effect indicates a common structure for these two families of proteins and opens the possibility for a meaningful survey of inhibitors of 6'-N-aminoglycoside acetyltransferase-2"-O-aminoglycoside phosphotransferase useful in clinical practice.

Acetyltransferases↗

PubMed1975

Aminoglycoside 3'-phosphotransferases I and II in Pseudomonas aeruginosa.

Aminoglycoside 3'-phosphotransferases I and II in three strains of Pseudomonas aeruginosa were studied in comparison with those in two strains of R factor-carrying Escherichia coli. The strain TI-13 of P. aeruginosa produced the former and strain H-9 the latter. Strain B-13 produced the both enzymes. The 3'-phosphotransferases of type I in P. aeruginosa TI-13, B-13 and E. coli K12 J5 R11-2 were different from each other in chromatographic behavior, molecular weight, pH optimum, and Ii. The 3'-phosphotransferase of type II in P. aeruginosa H-9 and E. coli JR66/W677 showed the same behavior.

Aminoglycosides↗

PubMed1991

Hereditary erythrocyte adenylate kinase deficiency: a defect of multiple phosphotransferases?

Adenylate kinase (AK) modulates the interconversion of adenine nucleotides (AMP + adenosine triphosphate----2 ADP). We evaluated the fifth kindred with hereditary erythrocyte (RBC) AK deficiency. The proband had chronic hemolytic anemia. Her RBC had undetectable AK activity when measured spectrophotometrically, whereas those of her parents had half-normal AK activity. AK electrophoresis showed only AK-1 in the parents. The activities of pyruvate kinase and phosphoribosylpyrophosphate synthetase were decreased given the young age of the proband's RBC. Despite the absence of spectrophotometric AK activity, the proband's RBC were able to incorporate 14C-adenine into 14C-adenine nucleotides at 50% of the rate expected for her young RBC population, suggesting the possibility of an alternative pathway for the formation of ADP from AMP. Normal hemolysate had AMP:guanosine triphosphate (GTP) phosphotransferase activity, which produced ADP at 8% to 9% of the rate of AK (6.8 +/- 0.8 IU/mL RBC). AMP:GTP phosphotransferase activity was not detectable in the proband's or parent's hemolysates. These additional biochemical defects in the AK-deficient RBC further support the concept that AK deficiency per se may not cause hemolytic anemia. We propose that defects occur in multiple phosphotransferases in the AK-deficient RBC and that these other biochemical defects may produce deleterious lesions that promote the shortened RBC survival in AK deficiency.

Adenosine Diphosphate↗

PubMed1990

Molecular cloning, transcriptional analysis, and nucleotide sequence of lacR, a gene encoding the repressor of the lactose phosphotransferase system of Lactococcus lactis.

The repressor gene (lacR) of the lactose phosphotransferase system of Lactococcus lactis subsp. lactis strain MG1820 has been cloned and characterized. Transcription of lacR, into a 1.2-kilobase monocistronic messenger, is repressed approximately 5-fold during growth on lactose. Nucleotide sequence analysis of the lacR gene showed the presence of an open reading frame of 861 base pairs. The deduced amino acid sequence of LacR is homologous to three Escherichia coli regulatory proteins (DeoR, FucR, and GutR) and includes a N-terminal domain (helix-turn-helix) involved in DNA binding and a C-terminal domain that may be responsible for inducer binding. The in vivo function of LacR has been determined by introducing multiple copies of lacR into L. lactis, under control of its own or the unrelated prtP promoter. Growth rates and lactose phosphotransferase system enzyme activities were measured during growth on lactose and glucose. The presence of lacR on a multicopy plasmid resulted in the decrease of lactose phosphotransferase system activity, whereas only on lactose a decrease (25%) of growth rate was observed. No significant difference in growth rate was observed on glucose, indicating that LacR specifically represses the lactose genes of L. lactis.

Amino Acid Sequence↗

PubMed1990

[Carbohydrate phosphotransferase in human hepatoma and phosphorylation of cathepsin D].

Two enzymes (N-acetylglucosamine-1-phosphotransferase and phosphodiester glycosidase) involved in formation of mannose-6-phosphate at lysosomal hydrolases were studied for the activity and kinetics in human hepatocellular carcinoma. The activity level of the phosphotransferase with an artificial substrate was elevated (p less than 0.025) in hepatoma compared to that in normal liver, while the phosphodiester glycosidase of hepatoma was in a similar level with that of control. The elevation was more remarkable with a physiological substrate, cathepsin D. (P less than 0.001). Since cathepsin D from normal liver was previously demonstrated to contain less phosphomannose compared to the hepatoma protease, the protease was investigated for carbohydrate phosphorylation by the phosphotransferase. The liver protease was much more phosphorylated than the hepatoma protease, endorsing the previous observation. The predominant phosphorylation of the protease occurred in heavy subunit.

Carcinoma, Hepatocellular↗

PubMed1979

Purification of the mannitol-specific enzyme II of the Escherichia coli phosphoenolpyruvate:sugar phosphotransferase system.

The inducible, mannitol-specific Enzyme II of the phosphoenolpyruvate:sugar phosphotransferase system has been purified approximately 230-fold from Escherichia coli membranes. The enzyme, initially solubilized with deoxycholate, was first subjected to hydrophobic chromatography on hexyl agarose and then purified by several ion exchange steps in the presence of the nonionic detergent, Lubrol PX. The purified protein appears homogeneous by several criteria and probably consists of a single kind of polypeptide chain with a molecular weight of 60,000 (+/- 5%). In addition to catalyzing phosphoenolpyruvate-dependent phosphorylation of mannitol in the presence of the soluble enzymes of the phosphotransferase system, the purified Enzyme II also catalyzes mannitol 1-phosphate:mannitol transphosphorylation in the absence of these components. A number of other physical and catalytic properties of the enzyme are described. The availability of a stable, homogeneous Enzyme II should be invaluable for studying the mechanism of sugar translocation and phosphorylation catalyzed by the bacterial phosphotransferase system.

Escherichia coli↗

PubMed1984

Multiple forms of pyrophosphate:D-fructose-6-phosphate 1-phosphotransferase from wheat seedlings. Regulation by fructose 2,6-bisphosphate.

Two forms of pyrophosphate:D-fructose-6-phosphate 1-phosphotransferase have been isolated from wheat seedlings. One of these enzymes, termed PFP-1, has been purified to homogeneity. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicates that the enzyme is composed of two different polypeptide chains of Mr = 67,000 (alpha) and 60,000 (beta). PFP-1 has been assigned a molecular structure consisting of alpha 2 beta 2 based on an estimated Mr of 234,000 for the native enzyme. PFP-2, the other form of phosphotransferase, has also been purified extensively. Preliminary data suggest that the active form of PFP-2 is probably a dimer of a polypeptide chain of Mr = 60,000. Immunological studies indicate that the two enzyme preparations share common antigenic determinants. The two forms of enzyme have very similar kinetic properties. The phosphotransferases are activated by fructose 2,6-bisphosphate (Fru-2,6-P2) which lowers the Km of the enzymes for fructose 6-phosphate but not that for PPi. Interestingly, PFP-1 is significantly more active than PFP-2 in the absence of Fru-2,6-P2. Also, PFP-1 exhibits a greater affinity (Ka = 7 nM) than PFP-2 (Ka = 26 nM) for the activator. Based on kinetic, immunological, and physicochemical parameters, it is suggested that the two enzymic forms are related in that they share the same catalytic moiety, i.e. the 60,000-dalton or beta subunit. The beta subunit when in complex formation with the alpha subunit, as in PFP-1, becomes more active in the absence of Fru-2,6-P2 as well as exhibits a greater sensitivity toward the effector.

Enzyme Activation↗

PubMed1976

Sugar transport. Properties of mutant bacteria defective in proteins of the phosphoenolpyruvate: sugar phosphotransferase system.

The bacterial phosphotransferase system (PTS) catalyzes the transfer of the phosphoryl group from phosphoenolpyruvate to its sugar substrates, PTS sugars, concomitant with the translocation of these sugars across the bacterial membrane. The phosphorylation of a given sugar requires four proteins, two general proteins, Enzyme I, and the histidine-containing phosphocarrier protein of the PTS (HPr), used for all sugars, and a pair of proteins specific for that sugar, designated an Enzyme II complex. The phosphotransferase system has been implicated in regulating the induction of synthesis of some catabolic enzyme systems required for the utilization of sugars that are not substrates of the phosphotransferase system, and this and the accompanying reports are concerned with this phenomenon in Salmonell typhimurium and Escherichia coli. Mutants defective in Enzyme I (ptsI), HPr (ptsH), and certain Enzymes II were isolated, and their abilities to ferment and grow on a wide range of sugars and other compounds were determined. The mutants showed the expected properties on PTS sugars, but in addition, ptsH and tight ptsI mutants were unable to utilize certain non-PTS sugars, including maltose, melibiose, glycerol, glycerol-P, mannose-6-P, and, in E. coli, lactose. Leaky Enzyme I mutants could utilize these carbohydrates, but were unable to use them in the presence of a PTS sugar such as methyl alpha-D-glucopyranoside. In accord with the results reported by other laboratories, the inability of the mutants to utilize the non-PTS sugars was explained by the fact that these cells could not be normally induced to synthesize the corresponding catabolic enzyme systmes. This phenomenon is designated PTS-mediated repression. PTS-mediated repression was also observed in wild type cells, but by comparing wild type and leaky pts mutants it was shown that the sensitivity to repression by PTS sugars was greatest in mutants containing the lowest levels of Enzyme I or HPr. Furthermore, ptsI mutants containing a second site mutation in a gene for an Enzyme II were not repressed by the sugar substrate of that Enzyme II, although repression by other PTS sugars was not affected. Transport and other studies further indicated that neither appreciable uptake nor metabolism of the PTS sugars was required for these compounds to effect repression. The ptsH mutants showed the same phenotypic properties as the ptsI mutants with some important exceptions. First, they could ferment and grow on a PTS sugar, fructose. Second, after growth on fructose, (and to a lesser extent on glucose or mannose), such mutants were capable of utilizing other PTS sugars for a few generations. Third, growth of the ptsH mutants on fructose relieved PTS-mediated repression; after growth on fructose, but not on lactate, the mutants could grow for several generations on non-PTS sugars. Preliminary experiments indicated that growth on fructose resulted in the formation of one or more proteins that could substitute for HPr in the utilization of both PTS and non-PTS sugars.

Acetylglucosamine↗

PubMed1993

Unique monocistronic operon (ptsH) in Mycoplasma capricolum encoding the phosphocarrier protein, HPr, of the phosphoenolpyruvate:sugar phosphotransferase system. Cloning, sequencing, and characterization of ptsH.

The region of the genome of Mycoplasma capricolum encompassing the gene (ptsH) encoding HPr, a general energy-coupling protein of the phosphoenolpyruvate:sugar phosphotransferase system, was cloned and sequenced. Examination of the sequence revealed a unique arrangement of the ptsH gene. In all other bacterial species characterized thus far, the ptsH gene is part of a polycistronic operon that includes the gene (ptsI) encoding Enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system; the M. capricolum ptsH gene is part of a monocistronic operon that is situated between two open reading frames unrelated to phosphoenolpyruvate:sugar phosphotransferase system function. The gene immediately upstream of ptsH codes for a helicase, and the open reading frame immediately downstream of ptsH, although not homologous to any previously identified protein, contains a signature sequence characteristic of [C-5] cytosine-specific DNA methylases. The product of the ptsH gene has characteristics similar to the HPr protein produced by Gram-positive organisms: it has a greater sequence similarity to HPrs of Gram-positive bacteria than to those of Gram-negative organisms, it is phosphorylated by a protein kinase derived from Gram-positive organisms, and it complements sugar phosphorylation activity in Gram-positive extracts. The high calculated isoelectric point (pI = 9.18) and the absence of glutamate residues in the C-terminal region distinguish the M. capricolum HPr from all previously described HPrs.

Amino Acid Sequence↗

PubMed1996

Effect of polyamines on plasmid-mediated kanamycin resistance and kanamycin phosphotransferase gene expression in Escherichia coli.

The emergence of kanamycin resistance in a polyamine-deficient mutant of E. coli transformed with a plasmid encoding the kanamycin phosphotransferase gene has been studied. The initial inhibition of growth and protein synthesis caused by the addition of the antibiotic could be reversed earlier in polyamine-supplemented bacteria than in those depleted of the organic bases. Concomitantly, we have observed that the increase of kanamycin phosphotransferase activity evoking the antibiotic resistance was higher in bacteria cultivated in the presence of putrescine. This result seems to depend exclusively on the enhanced capacity of the translation process in bacteria grown with polyamines since the transcription of phosphotransferase gene was higher in cells subjected to polyamine starvation.

Bacterial Proteins↗

PubMed1984

Interaction between IIIGlc of the phosphoenolpyruvate:sugar phosphotransferase system and glycerol kinase of Salmonella typhimurium.

Purified IIIGlc of the phosphoenolpyruvate:sugar phosphotransferase system of Salmonella typhimurium inhibits glycerol kinase. Phosphorylation of IIIGlc via phosphoenolpyruvate, enzyme I, and HPr abolishes this inhibition. The glycerol facilitator is not inhibited by IIIGlc. It is proposed that regulation of glycerol metabolism by the phosphoenolpyruvate:sugar phosphotransferase system is at the level of glycerol kinase.

Bacterial Proteins↗

PubMed2004

A novel mutation in UDP-N-acetylglucosamine-1-phosphotransferase gamma subunit (GNPTAG) in two siblings with mucolipidosis type III alters a used glycosylation site.

The N-acetylglucosaminyl-1-phosphotransferase (termed phosphotransferase) catalyzes the initial step in the formation of mannose 6-phosphate (M6P) residues required for the efficient transport of soluble lysosomal enzymes. The phosphotransferase is a multisubunit enzyme composed of three subunits (alpha2beta2gamma2) that are products of two genes. The gene encoding the gamma-subunit (GNPTAG) appears to be defective in patients with mucolipidosis type III (ML III). We have analyzed the GNPTAG gene in two siblings with ML III showing elevated activities of several lysosomal enzymes in cultured fibroblasts serum and diminished activities in cultured fibroblasts. Immunoprecipitation of metabolically labeled cathepsin D (CtsD) from fibroblasts revealed that the sorting/transport of this lysosomal protease was affected. Addition of ammonium chloride inhibiting pH-dependent processes, such as the CtsD-M6P receptor interaction, indicated that 15 to 20% of the newly synthesized CtsD is transported in ML III fibroblasts in an M6P-dependent manner. By direct sequencing a novel homozygous mutation, c.347_349delACA (p.Asn116del), was identified affecting a potential N-linked glycosylation site. Western blot analysis of extracts from control fibroblasts detect a 97 kDa glycosylated dimer whereas ML III cells contain a GNPTAG dimer of reduced molecular mass. These data suggest that the loss of the used glycosylation site in the gamma subunit may affect the intracellular localization of GNPTAG and the overall efficiency of M6P formation.

Binding Sites↗

PubMed2005

Mucolipidosis II is caused by mutations in GNPTA encoding the alpha/beta GlcNAc-1-phosphotransferase.

Mucolipidosis II (ML II) is a fatal lysosomal storage disorder resulting from defects in the multimeric GlcNAc-1-phosphotransferase responsible for the initial step in the generation of the mannose 6-phosphate (M6P) recognition marker. M6P residues on oligosaccharides of newly synthesized lysosomal enzymes are essential for efficient receptor-mediated transport to lysosomes. We used the recombinant GlcNAc-1-phosphotransferase gamma subunit as an affinity matrix to purify an unknown protein identified as the product of GNPTA (encoding GNPTA, previously known as MGC4170). The cDNA encodes a protein of 1,256 amino acids with two putative transmembrane domains and a complex preserved modular structure comprising at least six domains. The N-terminal domain of GNPTA, interrupted by a long insertion, shows similarities to bacterial capsule biosynthesis proteins. We identified seven mutations in GNPTA that lead to premature translational termination in six individuals with ML II. Retroviral transduction of fibroblasts from an individual with ML II resulted in the expression and localization of GNPTA in the Golgi apparatus, accompanied by the correction of hypersecretion of lysosomal enzymes. Our results provide evidence that GNPTA encodes a subunit of GlcNAc-1-phosphotransferase defective in individuals with ML II.

Amino Acid Sequence↗

PubMed1995

Characterization and partial purification of a novel enzymatic activity. UDP-GlcNAc:Ser-protein N-acetylglucosamine-1-phosphotransferase from the cellular slime mold Dictyostelium discoideum.

An enzymatic activity that transfers N-acetylglucosamine-1-phosphate residues from UDP-GlcNAc to serine units in proteins (UDP-GlcNAc:Ser-protein N-acetylglucosamine-1-phosphotransferase) was detected in membranes of the cellular slime mold Dictyostelium discoideum. The enzyme was partially purified by affinity chromatography in concanavalin A-Sepharose and ion exchange chromatography in a Mono Q column. The enzyme showed an absolute requirement for bivalent cations, Mn2+ being more effective than Mg2+. It had a broad optimum pH value (6.5-9.0). The Km for UDP-GlcNAc was 18 microM. In cell free assays it used apomucin and native or 8 M urea-denatured thyroglobulin but neither bovine serum albumin nor native or denatured uteroferrin as exogenous acceptors. Analysis of proteins isolated from cells grown in the presence of [32P]phosphate and from the culture medium showed that the majority of proteins bearing the structure Glc-NAc-1-P-Ser were secreted. In equilibrium density centrifugations of microsomes, the enzyme appeared in membranes having lighter densities than the enzyme that phosphorylates high mannose-type oligosaccharides. This showed that the activity that phosphorylates serine residues in proteins (UDP-GlcNAc:Ser-protein N-acetylglucosamine-1-phosphotransferase) is different from that phosphorylating protein-linked high mannose-type oligosaccharides (UDP-GlcNAc:glycoprotein N-acetylglucosamine-1-phosphotransferase).

Animals↗

PubMed1995

Strain-dependent occurrence of functional GTP:AMP phosphotransferase (AK3) in Saccharomyces cerevisiae.

The gene for yeast GTP:AMP phosphotransferase (PAK3) was found to encode a nonfunctional protein in 10 laboratory strains and one brewers' strain. The protein product showed high similarity to vertebrate AK3 and was located exclusively in the mitochondrial matrix. The deduced amino acid sequence revealed a protein that was shorter at the carboxyl terminus than all other known adenylate kinases. Introduction of a +1 frameshift into the 3'-terminal region of the gene extended homology of the deduced amino acid sequence to other members of the adenylate kinase family including vertebrate AK3. Frameshift mutations obtained after in vitro and in vivo mutagenesis were capable of complementing the adk1 temperature-conditional deficiency in Escherichia coli, indicating that the frameshift led to the expression of a protein that could phosphorylate AMP. Some yeasts, however, including strain D273-10B, two wine yeasts, and two more distantly related yeast genera, harbored an active allele, named AKY3, which contained a +1 frameshift close to the carboxyl terminus as compared with the laboratory strains. The encoded protein exhibited GTP:AMP and ITP:AMP phosphotransferase activities but did not accept ATP as phosphate donor. Although single copy in the haploid genome, disruption of the AKY3 allele displayed no phenotype, excluding the possibility that laboratory and brewers' strains had collected second site suppressors. It must be concluded that yeast mitochondria can completely dispense with GTP:AMP phosphotransferase activity.

Alleles↗

PubMed1997

Several cooperating binding sites mediate the interaction of a lysosomal enzyme with phosphotransferase.

Lysosomal targeting of soluble lysosomal hydrolases is mediated by mannose 6-phosphate receptors, which recognize and bind mannose 6-phosphate residues in the oligosaccharide chains of proteins destined for delivery to lysosomes. This recognition marker is generated by the sequential action of two enzymes, the first of which, UDP-N-acetylglucosamine phosphotransferase, recognizes lysosomal enzymes on the basis of a structural determinant in their polypeptide chains. This recognition event is a key step in lysosomal targeting of soluble proteins, but the exact nature of the recognition determinant is not well understood. In this study we have characterized the phosphotransferase recognition signals of human lysosomal aspartylglucosaminidase (AGA) using transient expression of polypeptides carrying targeted amino acid substitutions. We found that three lysine residues and a tyrosine residing in three spatially distinct regions of the AGA polypeptide are necessary for phosphorylation of the oligosaccharides. Two of the lysines are especially important for the lysosomal targeting efficiency of AGA, which seems to be mostly dictated by the degree of phosphorylation of the alpha subunit oligosaccharide. On the basis of the results of this and previous studies we suggest a general model for recognition of lysosomal enzymes by the phosphotransferase.

Aspartylglucosylaminase↗

PubMed1982

Regulation by Lipids of Plant Microsomal Enzymes: III. Phospholipid Dependence of the Cytidine-Diphospho-Choline Phosphotransferase of Potato Microsomes.

Cytidine-diphospho-choline diacyl-glycerol phosphorylcholine phosphotransferase activity was demonstrated in potato (Solanum tuberosum L.) microsomes and the incorporation of cytidine-diphospho[(14)C]choline into phosphatidylcholine was characterized by the time course of (14)C incorporation and the effect of microsomal protein concentration on choline incorporation.Potato microsomes were progressively delipidated by treatments (2 min at 0 degrees C) with increasing amounts of phospholipase C from Bacillus cereus. A decrease in choline phosphotransferase activity was observed in parallel with the progressive hydrolysis of membrane phospholipids. A 70% (or more) phospholipid hydrolysis provoked the total inactivation of the enzyme.Adding back exogenous phospholipids (in the form of liposomes) to phospholipase C-treated membranes restored the enzymic activity. Restoration could be obtained with egg yolk phospholipids as well as with potato phospholipids. Restoration was time dependent and completed after 10 minutes; restoration was also dependent on the quantity of liposomes added to lipid-depleted membranes: the best restorations were obtained with 1 to 2.5 milligrams of phospholipid per mg of microsomal protein; higher phospholipid to protein ratios were less efficient or inhibitory.These results clearly demonstrate the phospholipid dependence of the cytidine-diphospho-choline phosphotransferase from potato microsomes.

Journal Article↗