In vitro synthesis and O acetylation of peptidoglycan by permeabilized cells of Proteus mirabilis.

The synthesis and O acetylation in vitro of peptidoglycan by Proteus mirabilis was studied in microorganisms made permeable to specifically radiolabelled nucleotide precursors by treatment with either diethyl ether or toluene. Optimum synthesis occurred with cells permeabilized by 1% (vol/vol) toluene in 30 mM MgCl2 in in vitro experiments with 50 mM Tris-HCl buffer (pH 6.80). Acetate recovered by mild base hydrolysis from sodium dodecyl sulfate-insoluble peptidoglycan synthesized in the presence of UDP-[acetyl-1-14C]N-acetyl-D-glucosamine was found to be radioactive. Radioactivity was not retained by peptidoglycan synthesized when UDP-[acetyl-1-14C]N-acetyl-D-glucosamine was replaced with both unlabelled nucleotide and either [acetyl-3H]N-acetyl-D-glucosamine or [glucosamine-1,6-3H]N-acetyl-D-glucosamine. In addition, no radioactive acetate was detected in the mild base hydrolysates of peptidoglycan synthesized in vitro with UDP-[glucosamine-6-3H]N-acetyl-D-glucosamine as the radiolabel. Chasing UDP-[acetyl-1-14C]N-acetyl-D-glucosamine with unlabelled material served to increase the yield of O-linked [14C]acetate, whereas penicillin G blocked both peptidoglycan synthesis and [14C]acetate transfer. These results support the hypothesis that the base-labile O-linked acetate is derived directly from N-acetylglucosamine incorporated into insoluble peptidoglycan via N----O transacetylation and not from the catabolism of the supplemented peptidoglycan precursors followed by subsequent reactivation of acetate.     

Cadaverine is covalently linked to peptidoglycan in Selenomonas ruminantium.

Cadaverine was found to exist as a component of cell wall peptidoglycan of Selenomonas ruminantium, a strictly anaerobic bacterium. [14C]cadaverine added to the growth medium was incorporated into the cells, and about 70% of the total radioactivity incorporated was found in the peptidoglycan fraction. When the [14C]cadaverine-labeled peptidoglycan preparation was acid hydrolyzed, all of the 14C counts were recovered as cadaverine. The [14C]cadaverine-labeled peptidoglycan preparation was digested with lysozyme into three small fragments which were radioactive and were positive in ninhydrin reaction. One major spot, a compound of the fragments, was composed of alanine, glutamic acid, diaminopimelic acid, cadaverine, muramic acid, and glucosamine. One of the two amino groups of cadaverine was covalently linked to the peptidoglycan, and the other was free. The chemical composition of the peptidoglycan preparation of this strain was determined to be as follows: L-alanine-D-alanine-D-glutamic acid-meso-diaminopimelic acid-cadaverine-muramic acid-glucosamine (1.0:1.0:1.0:1.0:1.1:0.9:1.0).     

Inhibition of peptidoglycan biosynthesis at a postcytoplasmic reaction in a stable L-phase variant of Streptococcus faecium.

Cultures of a stable L-phase variant of Streptococcus faecium F24 produced and retained peptidoglycan precursors intracellularly over the entire growth cycle in a chemically defined medium. The identity of the most abundant precursor, UDP N-acetylmuramyl-L-alanyl-D-glutamyl-L-lysyl-D-alanyl-D-alanine (UDP-MurNAc-pentapeptide), was confirmed by demonstrating in vitro the presence of enzymes required for the cytoplasmic stage of peptidoglycan biosynthesis. The initial membrane-bound reaction in peptidoglycan biosynthesis involving phospho-MurNAc-pentapeptide translocase and undecaprenyl-phosphate membrane carrier was catalyzed by protoplast membrane preparations but not by L-phase membrane preparations. However, both protoplast and L-phase membranes incorporated radioactivity from dTDP-L-[14C]rhamnose, the presumed precursor to a non-peptidoglycan cell surface component, into high-molecular-weight material. dTDP-L-rhamnose did not accumulate in growing cultures but was synthesized from D-glucose-1-phosphate and dTTP by cell-free extracts of the streptococcus and L-phase variant. Neither rhamnose- nor muramic acid-containing compounds were detected in culture fluids. It is suggested that continued inhibition of cell wall biosynthesis in this stable L-phase variant is the result of a defect expressed at the membrane stage of peptidoglycan biosynthesis specifically involving the translocation step.     

Biosynthesis of peptidoglycan in Gaffkya homari. The mode of action of penicillin G and mecillinam.

The effect of the beta-lactam antibiotics penicillin G and mecillinam on the incorporation of peptidoglycan into pre-formed cell wall peptidoglycan was studied with wall membrane enzyme preparations from Gaffkya homari. Using UDP-N-acetylglucosamine (UDP-GlcNAc) and UDP-N-acetylmuramyl-pentapeptide (UDP-MurNAc-pentapeptide) as precursors the incorporation of peptidoglycan into the pre-existing cell wall of G. homari was inhibited to an extent of 50% (ID50 value) at a concentration of 0.25 mug of penicillin G/ml. With UDP-GlcNAc and UDP-MurNAc-tetrapeptide as precursors the ID50 value was about 2500-fold greater (630 mug/ml). The inhibition by penicillin G of the incorporation of peptidoglycan from UDP-MurNAc-[14C]Lys-pentapeptide could be overcome by addition of non-radioactive UDP-MurNAc-tetrapeptide to the incubation mixture. In the presence of 5 mug of penicillin G/ml the incorporation of peptidoglycan formed from the mixture of UDP-MurNAc-Ala-DGlu-Lys-D-[14C]Ala-D[14C]Ala and non-radioactive UDP-MurNAc-tetrapeptide proceeded virtually without release of D-[14C]alanine by transpeptidase activity. The enzyme preparation also exhibited DD-carboxypeptidase activity which was only slightly more sensitive to penicillin G and mecillinam than was the incorporation of peptidoglycan into the cell wall. Since the ID50 values for the beta-lactam antibiotics are similar to the concentrations required to inhibit the growth of G. homari to an extent of 50%, the DD-carboxypeptidase must be the killing site of both penicillin G and mecillinam.     

Temperature-dependent variation in the synthesis of streptococcal group-specific carbohydrate. II. Biosynthetic studies in group A and variant strains.

The biosynthesis of the cell wall polysaccharide and peptidoglycan of group A and A-486-Var streptococci was studied with N-acetyl-[14C]glucosamine, UDP-N-acetyl-[14C]glucosamine, and [14C]glucose. The incorporation of N-acetyl-[14C]-glucosamine into the cell wall four times greater in the A-486-Var cells than in the group A cells. However, the percentage of the total label incorporated into the cell wall polysaccharide at 37 degrees C by the A-486-Var strain was 12%, compared with 66% for the group A cells. When the A-486-Var was grown at 22 degrees C, the proportion of the label incorporated into the cell wall polysaccharide increased to 41%. At 37 degrees C, N-acetyl-[14C]glucosamine was incorporated preferentially into the peptidoglycan of the A-486-Var; almost three times as much of the label was incorporated into the peptidoglycan at 37 degrees C as was incorporated at 22 degrees C. Studies with protoplast membranes of these organisms showed similar differences, with a fourfold greater uptake of UDP-N-acetyl-[14C]glucosamine by the A-486-Var membranes at both incubation temperatures. These studies suggest that a defect in the incorporation of N-acetylglucosamine into the side chain of the polysaccharide is present in the A-486-Var strain at a step following the synthesis of UDP-N-acetylglucosamine. This defect, which may involve the UDP-N-acetylglucosamine transferase, is temperature dependent in the A-486-Var strain.     

Characterization of particulate D-apiosyl-and D-xylosyltransferase from Lemna minor.

A particulate enzyme preparation capable of catalyzing the transfer of d-[U-¹⁴C]apiose and d-[U-¹⁴C]xylose from uridine 5′-(α-d-[U-¹⁴C]apio-d-furanosyl pyrophosphate) (UDP[U-¹⁴C]Api) and uridine 5′-(α-d-[U-¹⁴C]xylopyranosyl pyrophosphate) (UDP[U-¹⁴C]Xyl) to endogenous acceptor molecules was isolated from Lemna minor. The two enzymes were named UDP-d-apiose:acceptor d-apiosyltransferase and UDP-d-xylose:acceptor d-xylosyltransferase and were associated with particulate material sedimenting between 480 and 34,800g. The rate of d-[U-¹⁴C]apiose or d-[U-¹⁴C]xylose incorporation was proportional to the quantity of enzyme preparation used and was constant with time to 1.5 min. Both enzymes showed a pH optimum of 5.7 in citrate-phosphate buffer. The d-apiosyltransferase has a K_m for UDP[U-¹⁴C]Api of 4.9 μm. Bovine serum albumin and sucrose stimulated the rate of incorporation of both pentoses. Both enzymes rapidly lost activity; with our best conditions, approximately 50% of each enzyme activity was lost in 6 min at 25 °C or in 3 h at 4 °C. Incorporation of d-[U-¹⁴C]apiose was obtained in the absence of added uridine 5′-(α-d-galactopyranosyluronic acid pyrophosphate) (UDPGalUA); however, the addition of UDPGalUA not only almost doubled the rate of incorporation, but also increased the total incorporation of d-[U-^l4C]apiose and extended the proportional range of incorporation at 25 °C from 1.5 to 2 min.     

A transglucosylase that forms soluble glucosides found in membranes of a haptophycean alga

A particulate enzyme preparation isolated from Chrysochromulina chiton catalysed the transfer of [U-¹⁴C]-glucose from UDP [U-¹⁴C]-Glc to a water-soluble small molecular weight material. Chemical and enzymic analysis of this material showed that it was a phenolic compound to which are attached two β(1–3) glucosides. Properties of the UDP glucose: glucosyltransferase involved in the synthesis of this material have been studied. The UDP glucose glucosyl-transferase was found to be associated with the rough endoplasmic reticulum. A possible function of this phenolic compound in the orientation of membranes for the synthesis of scales in C. chiton has been discussed.     

Glycogen synthesis in the fungus Neurospora crassa.

An enzymic activity, obtained from Neurospora crassa, catalyzing the incorporation of [14C]glucose from ADP-[14C]glucose into a glucan of the glycogen type, is described. The properties of the ADPglucose : glycogen glucosyltransferase as compared with those of the already known UDP glucose : glycogen glucosyltransferase were studied. The radioactive products obtained with UDP-14C]glucose or ADP-[14C]glucose released all the radioactivity as maltose after alpha or beta amylase treatment. Glucose 6-phosphate stimulated the synthetase when UDP-[14C]glucose was the substrate but the stimulation was much greater with ADP-[14C]glucose as glucosyl donor. Glucose 6-phosphate plus EGTA gave maximal stimulation. The system was completely dependent &on the presence of a 'primer' of the alpha 1 leads to 4 glucan type.     

Synthesis, characterization and properties of uridine 5′-(α-d-apio-d-furanosyl pyrophosphate)

1. A method was developed for synthesizing UDP-apiose [uridine 5'-(alpha-d-apio-d-furanosyl pyrophosphate)] from UDP-glucuronic acid [uridine 5'-(alpha-d-glucopyranosyluronic acid pyrophosphate)] in 62% yield with the enzyme UDP-glucuronic acid cyclase. 2. UDP-apiose had the same mobility as uridine 5'-(alpha-d-xylopyranosyl pyrophosphate) when chromatographed on paper and when subjected to paper electrophoresis at pH5.8. When [(3)H]UDP-[U-(14)C]glucuronic acid was used as the substrate for UDP-glucuronic acid cyclase, the (3)H/(14)C ratio in the reaction product was that expected if d-apiose remained attached to the uridine. In separate experiments doubly labelled reaction product was: (a) hydrolysed at pH2 and 100 degrees C for 15min; (b) degraded at pH8.0 and 100 degrees C for 3min; (c) used as a substrate in the enzymic synthesis of [(14)C]apiin. In each type of experiment the reaction products were isolated and identified and were found to be those expected if [(3)H]UDP-[U-(14)C]apiose was the starting compound. 3. Chemical characterization established that the product containing d-[U-(14)C]apiose and phosphate formed on alkaline degradation of UDP-[U-(14)C]apiose was alpha-d-[U-(14)C]apio-d-furanosyl 1:2-cyclic phosphate. 4. Chemical characterization also established that the product containing d-[U-(14)C]apiose and phosphate formed on acid hydrolysis of alpha-d-[U-(14)C]apio-d-furanosyl 1:2-cyclic phosphate was d-[U-(14)C]apiose 2-phosphate. 5. The half-life periods for the degradation of UDP-[U-(14)C]apiose to alpha-d-[U-(14)C]apio-d-furanosyl 1:2-cyclic phosphate and UMP at pH8.0 and 80 degrees C, at pH8.0 and 25 degrees C and at pH8.0 and 4 degrees C were 31.6s, 97.2min and 16.5h respectively. The half-life period for the hydrolysis of UDP-[U-(14)C]-apiose to d-[U-(14)C]apiose and UDP at pH3.0 and 40 degrees C was 4.67min. After 20 days at pH6.2-6.6 and 4 degrees C, 17% of the starting UDP-[U-(14)C]apiose was degraded to alpha-d-[U-(14)C]apio-d-furanosyl 1:2-cyclic phosphate and UMP and 23% was hydrolysed to d-[U-(14)C]apiose and UDP. After 120 days at pH6.4 and -20 degrees C 2% of the starting UDP-[U-(14)C]apiose was degraded and 4% was hydrolysed.     

Evidence for N----O acetyl migration as the mechanism for O acetylation of peptidoglycan in Proteus mirabilis.

O-acetylated peptidoglycan was purified from Proteus mirabilis grown in the presence of specifically radiolabelled glucosamine derivatives, and the migration of the radiolabel was monitored. Mild-base hydrolysis of the isolated peptidoglycan (to release ester-linked acetate) from cells grown in the presence of 40 microM [acetyl-3H]N-acetyl-D-glucosamine resulted in the release of [3H]acetate, as detected by high-pressure liquid chromatography. The inclusion of either acetate, pyruvate, or acetyl phosphate, each at 1 mM final concentration, did not result in a diminution of mild-base-released [3H]acetate levels. No such release of [3H]acetate was observed with peptidoglycan isolated from either Escherichia coli incubated with the same radiolabel or P. mirabilis grown with [1,6-3H]N-acetyl-D-glucosamine or D-[1-14C]glucosamine. These observations support a hypothesis that O acetylation occurs by N----O acetyl transfer within the sacculus. A decrease in [3H]acetate release by mild-base hydrolysis was observed with the peptidoglycan of P. mirabilis cultures incubated in the presence of antagonists of peptidoglycan biosynthesis, penicillin G and D-cycloserine. The absence of free-amino sugars in the peptidoglycan of P. mirabilis but the detection of glucosamine in spent culture broths implies that N----O transacetylation is intimately associated with peptidoglycan turnover.     

Evidence for coupling between transport of UDP-glucose and its synthesis by membrane-bound pyrophosphorylase in Golgi apparatus of cat liver

Incubation of sealed vesicles of cat-liver Golgi apparatus with UDP[14C]glucose showed that the vesicles accumulated radioactivity. After Triton X-100 treatment or sonication of washed vesicles, soluble radiolabeled species were released and identified by paper chromatography as UDP[14C]glucose, [14C]glucose 1-phosphate and free glucose. In the incubation medium, UDPglucose was effectively protected by addition of dimercaptopropanol and UTP. Presence of glucose 1-phosphate and glucose within the vesicles most probably arose from luminal pyrophosphatase and phosphatase. A portion of the [14C]glucose moiety became covalently linked to endogenous acceptors. Uptake of UDPglucose was saturable and dependent on time and on the concentration of sugar nucleotide. Together, these results were consistent with a transport system for UDPglucose in Golgi vesicles. Furthermore, penetration rate was considerably higher with UDPglucose synthetized in situ from glucose 1-phosphate by membrane-bound pyrophosphorylase than from added UDPglucose: Vmax values were respectively 10 and 2 pmol/15 min per mg protein. This result allows the conclusion that a coupling between translocase and synthetase is involved in UDPglucose transport through Golgi apparatus membranes. The mechanism of this 'kinetic advantage' is discussed.     

Dolichol kinase activity: a key factor in the control of N-glycosylation in inner mitochondrial membranes

Inner mitochondrial membranes from liver contain a dolichol kinase which required CTP as a phosphoryl donor. Kinase activity was linear with protein concentration and unlike other reported kinases, activated almost equally well by Mg2+, Mn2+ or Ca2+. Thin-layer chromatography showed that the reaction product co-migrated with authentic dolichyl monophosphate. The phosphorylation of dolichol did not occur in presence of ATP, GTP or UTP but required exogenous dolichol for maximal activity. Newly synthesized [3H]dolichyl monophosphate has been shown to be glycosylated in the presence of GDP[14C]mannose or UDP[14C]glucose. The double labeled lipids formed by the sugar nucleotide-dependent reactions were identified respectively as [14C]mannosylphosphoryl[3H]dolichol and [14C]glucosylphosphoryl [3H]dolichol. These results are discussed in terms of regulation of N-glycosylation processes in inner mitochondrial membranes from liver.     

Incorporation of [14C]glucose from UDP[14C]glucose into a phosphoglycolipid by cell-free particulate systems of a moderately halophilic gram-negative bacterium, Pseudomonas halosaccharolytica ATCC 29423.

A glucosyl group from uridine diphosphate [U-14C]glucose is incorporated into a phosphoglycolipid, probably a glucosylphosphatidylglycerol, by a disrupted membrane enzyme preparation from a gram-negative, moderately halophilic bacterium, Pseudomonas halosaccharolytica ATCC 29423. The conversion of [14C]phosphatidylglycerol into phosphoglycolipid by the particulate preparation was also enhanced in the presence of non-labelled UDP-glucose. A chemical degradation study of labelled phosphoglycolipid showed the bulk of the radioactivity from UDP[U-14C]glucose to be associated with the glucose moiety, which also appeared to be attached to the hydroxyl group of a second glycerol.     

Purification and characterisation of a novel starch synthase selective for uridine 5′-diphosphate glucose from the red alga Gracilaria tenuistipitata

Red algae (Rhodophyceae) are photosynthetic eukaryotes that accumulate starch granules in the cytosol. Starch synthase activity in crude extracts of Gracilaria tenuistipitata Chang et Xia was almost 9-fold higher with UDP[U-¹⁴C]glucose than with ADP[U-¹⁴C]glucose. The activity with UDP[U-¹⁴C]glucose was sensitive to proteolytic and oxidative inhibition during extraction whilst the activity with ADP[U-¹⁴C]glucose appeared unaffected. This indicates the presence of separate starch synthases with different substrate specificities in G. tenuistipitata. The UDPglucose: starch synthase was purified and characterised. The enzyme appears to be a homotetramer with a native M_r of 580 kDa and displays kinetic properties similar to other α-glucan synthases such as stimulation by citrate, product (UDP) inhibition and broad primer specificity. We propose that this enzyme is involved in cytosolic starch synthesis in red algae and thus is the first starch synthase described that utilises UDPglucose in vivo. The biochemical implications of the different compartmentalisation of starch synthesis in red algae and green algae/plants are also discussed. Received: 29 January 1999 / Accepted: 11 March 1999     

Biosynthesis of isoprenoids in intact cells of Escherichia coli

Upon rehydration of lyophilized Escherichia coli cells with phosphate buffer containing [14C]isopentenyl pyrophosphate (IPP), 14C was incorporated into the cells. Radioactivity was found in ubiquinone-8, an unidentified precursor of ubiquinone-8, demethylmenaquinone-8 and phosphate esters of all-trans-octaprenol and cis, trans-polyprenols. On rehydration of the cells with the buffer containing geranyl pyrophosphate or farnesyl pyrophosphate in combination with [14C]IPP, higher radioactivity was incorporated into the above products and some radioactivity was found in free prenols. Fractionation of the 14C-labeled cells by sucrose-density gradient centrifugation before and after recultivation indicated that the size of 14C-labeled cells had changed during the recultivation. This shows that radioactivity of [14C]IPP was incorporated into live cells but not into dead cells. The metabolism of the radioactive products in the recultivated cells was examined. It was found that the unidentified precursor was converted to ubiquinone-8, but demethylmenaquinone-8 was not converted to menaquinone-8. "Lipid intermediates" in peptidoglycan synthesis increased in the logarithmic growth phase and decreased in the stationary phase. In the stationary phase, however, an increase in cis,trans-polyprenyl monophosphates was observed. These observations suggest the operation of the lipid cycle of peptidoglycan synthesis.     

A simplified method for the preparation of pure UDP[14C] glucose.

A two-step enzymatic synthesis of UDP[14C] glucose was described which resulted in high yield. Separation of product from labelled intermediates and other contaminants was achieved by a simple ion exchange chromatography method.     

Incorporation of UDPGlucose into Cell Wall Glucans and Lipids by Intact Cotton Fibers

The [¹⁴C] moiety from [³H]UDP[¹⁴C]glucose was incorporated by intact cotton fibers into hot water soluble, acetic-nitric reagent soluble and insoluble components, and chloroform-methanol soluble lipids; the [³H] UDP moiety was not incorporated. The ³H-label can be exchanged rapidly with unlabeled substrate in a chase experiment. The cell wall apparent free space of cotton fibers was in the order of 30 picomoles per milligram of dry fibers; 25 picomoles per milligram easily exchanged and about 5 picomoles per milligram more tightly adsorbed. At 50 micromolar UDPglucose, 70% of the [¹⁴C]glucose was found in the lipid fraction after both a short labeling period and chase. The percent of [¹⁴C]glucose incorporated into total glucan increased slightly with chase, but the fraction of total glucans incorporated into insoluble acetic-nitric reagent (cellulose) did increase within a 30-minute chase period. The data supports the concept that glucan synthesis, including cellulose, as well as the synthesis of steryl glucosides, acetylated steryl glucosides, and glucosyl-phosphoryl-polyprenol from externally supplied UDPglucose occurs at the plasma membrane-cell wall interface. The synthase enzymes for such synthesis must be part of this interfacial membrane system.     

Replacement of diaminopimelic acid by cystathionine or lanthionine in the peptidoglycan of Escherichia coli.

In Escherichia coli, auxotrophy for diaminopimelic acid (A2pm) can be suppressed by growth with exogenous cystathionine or lanthionine. The incorporation of cystathionine into peptidoglycan metabolism was examined with a dapA metC mutant, whereas for lanthionine, a dapA metA mutant strain was used. Analysis of peptidoglycan precursors and sacculi isolated from cells grown with epimeric cystathionine or lanthionine showed that meso-A2pm was totally replaced in the same position by either sulfur-containing amino acid. Moreover, mainly L-allo-cystathionine (95%) or meso-lanthionine (93%) was incorporated into the precursors and sacculi. For this purpose, a new, efficient high-pressure liquid chromatography (HPLC) technique for analysis of the cystathionine isomers was developed. The formation of the UDP-MurNAc tripeptide appeared to be a critical step, since the MurE synthetase accepted meso-lanthionine or D-allo- or L-allo-cystathionine in vitro as good substrates, although with higher Km values. Presumably, the 10-fold-higher UDP-MurNAc-L-Ala-D-Glu pool of cells grown with cystathionine or lanthionine ensured a normal rate of synthesis. The kinetic parameters of the MurF synthetase catalyzing the addition of D-alanyl-D-alanine were very similar for the meso-A2pm-,L-allo-cystathionine-, and meso-lanthionine-containing UDP-MurNAc tripeptides. HPLC analysis of the soluble fragments resulting from 95% digestion by Chalaropsis N-acetylmuramidase of the peptidoglycan material in isolated sacculi revealed that the proportion of the main dimer was far lower in cystathionine and lanthionine sacculi.     

Glycogen synthesis in the fungus Neurospora crassa

An enzymic activity, obtained from Neurospora crassa, catalyzing the incorporation of [¹⁴C]glucose from ADP-[¹⁴C]glucose into a glucan of the glycogen type, is described. The properties of the ADPglucose: glycogen glucosyltransferase as compared with those of the already known UDP glucose: glycogen glucosyltransferase were studied. The radioactive products obtained with UDP-[¹⁴C]glucose or ADP-[¹⁴C]glucose released all the radioactivity as maltose after α or β amylase treatment. Glucose 6-phosphate stimulated the synthetase when UDP-[¹⁴C]glucose was the substrate but the stimulation was much greater with ADP-[¹⁴C]glucose as glucosyl donor. Glucose 6-phosphate plus EGTA gave maximal stimulation. The system was completely dependent on the presence of a ‘primer’ of the α 1 → 4 glucan type.     

Galactosyltransferase activities in pancreas, liver and gut of the developing rat

Two galactosyltransferase activities (1 and 2) were measured in the pancreas, liver and gut of the developing rat embryo. 1. N-Acetylglucosamine:Galactosyltransferase. UDP [¹⁴C]galactose + N-acetylglucosamine → [¹⁴C]galactosyl-β-(1 → 4)-N-acetylglucosamine + UDP. 2. N-Acetylgalactosamine-protein:Galactosyltransferase. UDP [¹⁴C]galactose + N-acetylgalactosamine-protein → [¹⁴C]galactosyl-β-(1 → 3)-N-acetylgalactosamine-protein + UDP. Galactosyltransferases 1 and 2 increased in the pancreas, about 10- and 40-fold in specific activity, respectively, from 11 to 12 days in utero to birth. During this period the activities of both transferases in the liver were somewhat variable, but showed no definite trend. A drop in the level of galactosyltransferase 1 in the pancreas occurred at birth or shortly thereafter. The “Golgimarker” enzyme for liver, galactosyltransferase 1, may be absent or present at low levels in adult rat pancreas.Zymogen granule membrane preparations apparently are devoid of these galactosyltransferase activities. Bromodeoxyuridine, which inhibits the development of the synthetic capability of the specific exocrine proteins, had essentially no effect on the normal accretion of the galactosyltransferase activities in organ cultures of pancreatic rudiments from 13-day rat embryos.