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At least 613 records · Page 34Linked to original sources
PubMed1992

Expression of peptidylglycine alpha-amidating monooxygenase: an in situ hybridization and immunocytochemical study.

Peptide alpha-amidation, an essential posttranslational modification that confers bioactivity to many neuroendocrine peptides, is catalyzed by peptidylglycine alpha-amidating monooxygenase (PAM; EC 1.14.17.3). To complement our previous studies on the distribution of PAM in neuroendocrine organs, we have examined expression of the PAM gene in several endocrine tissues by in situ hybridization and immunocytochemistry. In all instances, the autoradiographic densities for PAM mRNA correlated with staining patterns for PAM immunoreactivity. Very high levels of PAM mRNA were found in all heart atrial cardiomyocytes, while much lower levels were present in ventricular cells. In the sublingual gland, PAM was expressed diffusely in both acinar and tubule cells. In contrast, expression of PAM was confined to granular convoluted tubule cells in the submaxillary gland. PAM was expressed at high levels in a subset of adrenal medullary chromaffin cells, and low levels of PAM mRNA and immunoreactivity were also detected in the adrenal cortex. PAM was found predominantly in the calcitonin-producing parafollicular C-cells in the thyroid gland and in the glucagon-containing A-cells in the endocrine pancreas. Collecting and distal tubule cells of the kidney expressed both PAM mRNA and immunoreactivity. The basal cells in testicular seminiferous tubules containing PAM may represent developing germ and Sertoli cells. The cellular localization of PAM within the thyroid gland, adrenal gland, testis, and pancreas correlated with known peptidergic systems, and some of the observed cellular heterogeneity in PAM mRNA expression and immunoreactivity may reflect differences in the levels of amidated peptide production. The expression of PAM in cells not known to produce high levels of alpha-amidated peptides may indicate the production of yet unidentified alpha-amidated bioactive peptides or alternative functions of the PAM protein.

Adrenal Medulla↗
PubMed1998

Glucagon-like peptide-1-(7-36)amide increases pulmonary surfactant secretion through a cyclic adenosine 3',5'-monophosphate-dependent protein kinase mechanism in rat type II pneumocytes.

Glucagon-like peptide-1 (GLP-1) receptor messenger RNA has been identified in cells considered type II pneumocytes that are involved in the synthesis and secretion of the pulmonary surfactant. In an attempt to open new insights into the control of surfactant secretion, we studied the effects of glucagon-related peptides in this process. Accordingly, type II pneumocytes were isolated from Wistar rat lungs and cultured overnight with [methyl-14C]choline, and then the basal and stimulated secretions of [14C]phosphatidylcholine were measured. GLP-1(7-36)amide stimulated phosphatidylcholine secretion in a concentration-dependent manner in the 1-100 nM range; the concentration of the peptide that produced a half-maximal response was 10 nM. Exendin-4 induced similar effects. No changes were observed when GLP-1-(1-37), GLP-2, or exendin-(9-39) was added to the medium. However, the latter reversed the stimulatory effects of GLP-1-(7-36)amide and exendin-4. A study of the mechanism through which GLP-1-(7-36)amide exerts its stimulatory effect was carried out using different agents that are well known stimulants of phosphatidylcholine secretion. GLP-1-(7-36)amide did not produce any change in the stimulatory effect observed with terbutaline or 8-bromo-cAMP, suggesting the involvement of a cAMP-dependent protein kinase in the stimulatory effect of this peptide on phosphatidylcholine secretion. It was further supported by the use of inhibitors of protein kinases and by the stimulation of cAMP production in type II pneumocytes incubated with either GLP-1-(7-36)amide or exendin-4.

Adrenergic beta-Agonists↗
PubMed2003

Production of C-terminal amidated recombinant salmon calcitonin in Streptomyces lividans.

Salmon calcitonin (sCT) is one of the many bioactive peptides that require C-terminal amidation for full biologic activity. To produce fully bioactive sCT in large scale, we constructed Streptomyces lividans [pMSA], an engineering Streptomyces strain. In the expression vector, glycine-extended sCT, the substrate for amidation, and rat alpha-amidating enzyme cDNA were cloned under the control of the strong constitutive promoter from the Streptomyces fradiae aph gene in pIJ680. Both were expressed in a secretory manner by the recombinant strain using the expression and secretion signals of melC1. Extracellularly expressed recombinant sCT was purified to near homogeneity and characterized by enzyme immunoassay, followed by direct amino-terminal sequencing. High-performance liquid chromatography, matrix-assisted laser desorption ionization-time-of-flight mass spectrometry, and bioassay in vivo demonstrated purified product to be equivalent to synthetic standard. Thus, the engineered Streptomyces strain can produce bioactive, C-terminal amidated recombinant sCT in the culture supernatant directly. The ease of the recombinant process, as well as its potential for scale-up, makes it adaptable to production demands for sCT, and it may be applied to other bioactive peptides that need C-terminal amidation.

Animals↗
PubMed1993

Binding specificity and signal transduction of receptors for glucagon-like peptide-1(7-36)amide and gastric inhibitory polypeptide on RINm5F insulinoma cells.

Glucagon-like peptide-1(7-36)amide (GLP-1(7-36) amide) and gastric inhibitory polypeptide (GIP), peptides of the glucagon family, stimulate insulin secretion in vitro and in vivo. They possess high N-terminal sequence homology. Binding studies with 125I-labelled GIP and 125I-labelled GLP-1(7-36)amide were performed in RINm5F insulinoma cells to investigate receptor specificity and to compare both receptors directly. Both binding sites were highly ligand-specific: GIP did not bind to the GLP-1(7-36)amide receptor and vice versa. Both peptides increased intracellular cyclic AMP levels; GLP-1(7-36)amide was 100-fold more potent in stimulating cyclic AMP production when compared with GIP. At ranges of 1-10 nmol GLP-1(7-36)amide/l and 0.1-10 nmol GIP/l, corresponding to submaximal binding concentrations, the hormones showed an additive effect on cyclic AMP production. The N-terminal portion of GIP was important for binding, as GIP(1-30) showed almost full binding and biological activity. GIP(17-42) bound in a concentration-dependent manner with approximately 500-fold lower potency than GIP. At concentrations of up to 10 mumol GIP(17-42)/l no stimulation of cyclic AMP was observed.

Animals↗
PubMed1988

Alpha-amidated peptides derived from pro-opiomelanocortin in human pituitary tumours.

Human pituitary tumours, obtained at surgery for Cushing's disease and Nelson's syndrome, were extracted and the content and molecular forms of pro-opiomelanocortin (POMC)-derived peptides determined by radioimmunoassay, gel chromatography, reversed-phase high-performance liquid chromatography (HPLC) and sequence analysis. In the tumours from patients with Cushing's disease the mean concentrations of amidated peptides relative to the total amount of POMC were as follows: alpha-MSH, 1.7%; amidated gamma-MSH (gamma 1-MSH), 8.5% and the peptide linking gamma-MSH and ACTH in the precursor (hinge peptide or joining peptide) in its amidated form (HP-N), 17.1%. The same relative concentrations in the tumours from patients with Nelson's syndrome were 8.5% (alpha-MSH), 7.5% (gamma 1-MSH) and 12.2% (HP-N). More than 95% of the ACTH(1-39) immunoreactivity eluted as synthetic ACTH(1-39) by gel chromatography and HPLC. The remaining ACTH(1-39) immunoreactivity eluted as partly glycosylated high molecular weight forms. All the alpha-MSH and its glycine-extended precursor ACTH(1-14) were of low molecular weight, mainly non- or mono-acetylated forms, but significant amounts of diacetylated analogues were also present. gamma 1-MSH and gamma 2-MSH immunoreactivities eluted as high molecular weight forms and were partly glycosylated. No low molecular weight forms of gamma 1-MSH or gamma 2-MSH could be detected in the pituitary tumours. Amidated hinge peptide was mainly of the 30 amino acid form. In conclusion, all the molecular forms of the amidated peptides detected in tumours from patients with Cushing's disease and Nelson's syndrome were similar to the molecular forms found in the normal human pituitary. The main difference between the tumours and the normal pituitary was the greater amount of peptides produced, particularly alpha-MSH and gamma 1-MSH.

Adrenocorticotropic Hormone↗
PubMed1990

Dexamethasone pretreatment of rat insulinoma cells decreases binding of glucagon-like peptide-1(7-36)amide.

The effect of dexamethasone on binding of glucagon-like peptide-1(7-36)amide (GLP-1(7-36)amide) to rat insulinoma-derived cells (RINm5F) was investigated. Preincubation of RINm5F cells with dexamethasone (100 nmol/l) for 24 h resulted in a decrease of GLP-1(7-36)amide binding to 55.0 +/- 8.16% (mean +/- S.E.M.), incubation for 48 h to 39.1 +/- 1.76%, and for 72 h to 15.5 +/- 4.35% of maximal binding. The GLP-1(7-36)amide-induced stimulation of cyclic AMP (cAMP) production was significantly decreased to 61.03 +/- 7.4% of maximum production in cells pretreated with dexamethasone (100 nmol/l) for 48 h. The decreased binding was due to a reduction of the receptor number while the receptor affinity remained unchanged. These inhibitory effects on binding and cAMP formation induced by dexamethasone were completely abolished when the antiglucocorticoid RU 38486 (100 nmol/l) was added during preincubation with dexamethasone. RU 38486 alone had no effects. Our data suggest that the biological action of GLP-1(7-36)amide at the B-cell may be modified by glucocorticoids.

Animals↗
PubMed1993

Biological effects and metabolic rates of glucagonlike peptide-1 7-36 amide and glucagonlike peptide-1 7-37 in healthy subjects are indistinguishable.

The biological effects and the metabolism of the intestinal hormone glucagonlike peptide-1 7-36 amide and glucagonlike peptide-1 7-37 were studied in normal healthy subjects. GLP-1 7-36 amide and GLP-1 7-37 equipotently stimulated insulin secretion (integrated hormone response 0-60 min, 631 +/- 211 vs. 483 +/- 177 pmol/h x L-1) and C-peptide secretion (integrated hormone response 9064 +/- 1804 vs. 9954 +/- 2031 pmol/h x L-1) and equipotently lowered plasma glucose (integrated decrease 48.3 +/- 5.7 vs. 46.2 +/- 8.4 mmol/h x L-1) and plasma glucagon (integrated decrease 80.4 +/- 24.3 vs. 156.0 +/- 34.6 pmol/h x L-1). Both GLP-1 7-36 amide and GLP-1 7-37 lowered the plasma concentration of free fatty acids significantly. The plasma half-lives of GLP-1 7-36 amide and GLP-1 7-37 were 5.3 +/- 0.4 vs. 6.1 +/- 0.8 min, and the metabolic clearance rates of the two peptides also were similar (14.6 +/- 2.4 vs. 12.2 +/- 1.0 pmol/kg x min). In conclusion, COOH-terminal amidation is neither important for the metabolism of GLP-1 nor for its effects on the endocrine pancreas.

Adult↗
PubMed1995

Reduction of the incretin effect in rats by the glucagon-like peptide 1 receptor antagonist exendin (9-39) amide.

Glucagon-like peptide 1 (7-37)/(7-36) amide (GLP-1) is derived from the intestinal proglucagon processing. It is considered an important insulin-releasing gut hormone. This study uses exendin (9-39) amide as a GLP-1 receptor antagonist to evaluate the contribution of GLP-1 to the incretin effect. Anesthetized rats were challenged by an intraduodenal glucose infusion to evaluate maximally occurring GLP-1 and gastric inhibitory polypeptide (GIP) plasma levels. Maximal immunoreactive (IR) GLP-1 plasma levels amounted to 10 pmol/l (IR-GIP 11 pmol/l). Exendin (9-39) amide abolished the insulin-stimulatory effect of 60 pmol of GLP-1 or of the GLP-1 agonist exendin-4 (0.5 nmol) injected as bolus, respectively. An intravenous bolus injection of 5.94 nmol of exendin (9-39) amide 3 min before enteral glucose infusion grossly reduced the total insulin secretory response (by 60%) and significantly increased circulating blood glucose levels (P < 0.05). In contrast, the GLP-1 antagonist left the insulin response after an intravenous glucose or glucose plus GIP (60 pmol) load unaltered. Our data support the concept that GLP-1 is an important incretin factor. Exendin (9-39) amide is a useful GLP-1 antagonist for in vivo studies.

Animals↗
PubMed2000

Peptide amidating activity in human bronchoalveolar lavage fluid: relationship to lung cancer, inflammation and infection.

The most common post-translational modification of peptide hormones, present in half of all neuroendocrine (NE) peptides, is alpha-amidation and this is necessary for the biological activity of the peptides. Peptides are alpha-amidated by the action of two enzymes: peptidylglycine alpha-hydroxylating monooxygenase (PHM) and peptidylamidoglycolate lyase (PAL). As the common pathway for the formation of amidated peptides, the enzymes may provide a better indication of the NE status of a tumour or tissue than the presence of any single amidated peptide. PHM and PAL enzyme activities were measured in 39 BL fluid specimens from patients undergoing bronchoscopy for diagnosis of lung cancer. The assays revealed that PHM levels were higher in a group of specimens from patients undergoing bronchoscopy for chest infection, inflammation, asthma, or pneumonia compared to a group of specimens in which malignant cells were seen. The presence of elevated levels of amidating enzymes in specimens with non-cancerous conditions may reflect events of promotional phase cancer biology occurring simultaneously with inflammatory and infectious processes.

Amidine-Lyases↗
PubMed1992

Isolation and structural determination of a novel TRH-like tripeptide, pyroGlu-Tyr-Pro amide, from alfalfa.

The tripeptide pyroGlu-Tyr-Pro amide was isolated from an aqueous extract prepared from dried alfalfa pellets. The tripeptide was quantitated using a competitive radioimmunoassay in which 125I-labeled thyrotropin-releasing hormone (TRH), is displaced from antibody specific to TRH (pyroGlu-His-Pro amide). The pyroGlu-Tyr-Pro amide was purified by passing the filtered extract through QAE-Sephadex A25 at pH 5, followed by open bed chromatography on C18 silica using an H2O/methanol gradient, then preparative high performance liquid chromatography (HPLC) on microbondapak C18 using a 10 mM HCl/methanol gradient, followed by G-10-Sephadex chromatography, SP-C25-Sephadex chromatography, QAE-Sephadex chromatography at pH 10.1, analytical HPLC on a microbondapak C18 column eluted with 10 mm HCl/acetonitrile, and analytical HPLC reverse phase chromatography on an APEX phenyl column eluted with H2O/acetonitrile. The tripeptide was essentially homogeneous after the final chromatography step, as judged by correspondence of immunoreactivity with A280. The sequence of the alfalfa tripeptide was determined to be Glu-Tyr-Pro by gas phase sequencing, after hydrolysis of pyroglutamic acid by mild acid hydrolysis. The mass of the alfalfa tripeptide was 389.1, as determined by fast ion bombardment mass spectroscopy, and was found to be identical to the mass of synthetic pyroGlu-Tyr-Pro amide. The sequence of the alfalfa tripeptide was also verified using B/E-linked scanning. I conclude that the tripeptide isolated from alfalfa differs from human thyrotropin-releasing hormone only by the substitution of tyrosine for histidine at position 2. The role of pyroGlu-Tyr-Pro amide in alfalfa is not known, but the existence of a family of thyrotropin-related peptides occurring in both the animal and the plant kingdoms indicates that the thyrotropin related peptides have a wide phylogenetic distribution.

Chromatography, Gel↗
PubMed2006

[Study on the acryl amide intake in the Beijing diet].

OBJECTIVE: A 24-hours recall study was performed to get the acryl amide intake in the Beijing diet. METHODS: 24 separate items bought in the Beijing Market were analyzed and 2460 diet lists (820 participants x 3 days) were calculated. RESULTS: The following mean intakes of acryl amide have been estimated (microg/dm): males 18.6, females 16.6. For the 97.5 percentile of the population the intake is estimated to: males 59.0, females 50.4. As dose calculated per kg bodyweight the mean intake becomes [microg/(kg bw x d)]: males 0.282, females 0.284. For the 97.5 percentile [microg/ (kg bw x d)]: males 0.898, females 1.007. The contribution of the different meals and to the intake was as follows: breakfast 20.48%, lunch 38.99%, dinner 39.42%, snacks 1.17%. CONCLUSION: The survey leads to the conclusion that lunch and dinner are significant sources of acryl amide in a typical Beijing diet even if they have relatively low levels of acryl amide. Chinese traditional breakfast food is also an important source of acryl amide in a typical Beijing.

Acrylamide↗
PubMed1991

Comparison of enzymatic semisyntheses of peptide amides: human growth hormone releasing factor and analogs.

Enzymatic semisyntheses of growth hormone releasing factor (GRF), a 44-residue peptide amide hormone, from C-terminal acid precursors, are compared. A recombinant alpha-amidating enzyme was used to convert the glycine-extended precursor, GRF(1-44)-Gly-OH, to GRF(1-44)-NH2 in an essentially quantitative fashion. Trypsin was used to convert the precursors, GRF(1-43)-OH and GRF(1-44)-OH, to GRF(1-44)-NH2 (60 and 15% conversion, respectively) in a 75% v:v N,N'-dimethylacetamide solution containing a large excess of leucine amide. Carboxypeptidase Y catalyzed transpeptidations of the precursors, GRF(1-44)-OH and [Ala44]-GRF(1-44)-OH, to GRF(1-44)-NH2 in aqueous leucine amide solutions were also attempted. The trypsin catalyzed direct amidation of [Ala15]-GRF(1-29)-OH in concentrated ammonium acetate/ammonia buffer (95% 1,4-butanediol cosolvent) to form the superactive analog, [Ala15]-GRF(1-29)-NH2 (ca. 25% conversion at equilibrium), is also described.

Amino Acid Sequence↗
PubMed1985

FMRF-amide-like substances in the leech. I. Immunocytochemical localization.

FMRF-amide-like immunoreactivity (FLI) was localized to approximately 50 neurons in each segmental ganglion of the medicinal leech using immunocytochemical techniques. Although most of these neurons were iterated in each segmental ganglion, some were more restricted in their segmental distribution. The head and tail ganglia likewise contained numerous FMRF-amide-like immunoreactive cells. In addition to cell bodies, many nerve processes and varicosities were also immunoreactive throughout the ganglion. All labeling of FLI was blocked by preabsorption of the anti-FMRF-amide antiserum with synthetic FMRF-amide. Using a combination of Lucifer Yellow cellular injection and indirect immunofluorescence techniques, we identified several of the neurons possessing FLI. Identified neurons included excitatory motor neurons (HE, RPE, LPE, AE, and L), the HA modulatory neuron, interneuron cell 204, and cells of unknown function (AP). The processes of HE motor neurons and HA modulatory neurons which innervate the heart tubes were also immunoreactive. These results indicate a role for FMRF-amide-like substances as neurochemical signals in the leech.

Animals↗
PubMed1985

The neuropeptide FMRF-amide decreases both the Ca2+ conductance and a cyclic 3',5'-adenosine monophosphate-dependent K+ conductance in identified molluscan neurons.

The molluscan neuropeptide FMRF-amide (10 to 50 microM) decreases the duration of the Ca2+-dependent action potential recorded in the cell body of identified neurons of the snail Helix aspersa (cells D3 and E2). In these neurons, FMRF-amide evokes a decrease of the Ca2+ current resulting from a decrease in Ca2+ conductance. In another single neuron, cell E11, FMRF-amide, besides evoking a decrease of the Ca2+ conductance, induces a decrease of the S-current (Klein, M., J. S. Camardo, and E. R. Kandel (1982) Proc. Natl. Acad Sci. U. S. A. 79: 5713-5717), a K+ current controlled by cyclic AMP. However, in this E11 cell, FMRF-amide also evokes a decrease of the amplitude of the Ca2+ spike plateau. As discussed in the preceding paper (Paupardin-Tritsch, D., L. Colombaioni, P. Deterre, and H. M. Gerschenfeld (1985) J. Neurosci. 5: 2522-2532), it is suggested that these FRMF-amide-induced modulations of ionic conductances involved in the Ca2+-dependent spike recorded in these neuronal somata may intervene in processes of presynaptic inhibition and facilitation.

Action Potentials↗
PubMed1989

A cysteine-histidine-aspartate catalytic triad is involved in glutamine amide transfer function in purF-type glutamine amidotransferases.

A family of four glutamine amidotransferases has a homologous glutamine amide transfer domain, designated purF-type, that is named after purF-encoded glutamine phosphoribosylpyrophosphate amidotransferase. The glutamine amide transfer domain of approximately 194 amino acid residues is at the NH2 terminus of the protein chain. Site-directed mutagenesis was used to replace several of the 9 invariant amino acids in the glutamine amide transfer domain of glutamine phosphoribosylpyrophosphate amidotransferase. The results indicate that a Cys1-His101-Asp29 catalytic triad is involved in the glutamine amide transfer function of this enzyme. The evidence suggests that His101 functions to increase the nucleophilicity of Cys1, which is used to form a glutamine-enzyme covalent intermediate. Asp29 has a role subsequent to formation of the covalent intermediate. The Cys-His-Asp catalytic triad is implicated in the glutamine amide transfer function of purF-type amidotransferases.

Amino Acid Sequence↗
PubMed1989

Protein kinase inhibitor-(6-22)-amide peptide analogs with standard and nonstandard amino acid substitutions for phenylalanine 10. Inhibition of cAMP-dependent protein kinase.

The minimal structure in the heat-stable inhibitor protein of cAMP-dependent protein kinase required for a low nanomolar potency of inhibition is the peptide Thr6-Tyr-Ala-Asp-Phe-Ile-Ala-Ser-Gly-Arg-Thr-Gly-Arg-Arg-Asn-Ala-+ ++Ile22-NH2 (PKI-(6-22)-amide). While primary structural determinants for interaction with the protein kinase are distributed throughout the 17 residues of this peptide, we have previously shown that phenylalanine 10 in the NH2-terminal portion is a particularly important determinant for high affinity binding (Glass, D. B., Cheng, H.-C., Mende-Mueller, L., Reed, J., and Walsh, D. A. (1989) J. Biol. Chem. 264, 8802-8810). To investigate this requirement further, peptide analogs of PKI-(6-22)-amide in which various natural and nonstandard amino acids are substituted for phenylalanine 10 have been synthesized and tested for inhibitory potency against the catalytic subunit of the protein kinase. Consistent with the importance of the hydrophobicity of phenylalanine, an alanine 10 substitution analog exhibited a 270-fold decrease in inhibitory potency, whereas the leucine 10 analog lost only 33-fold in activity as compared to the parent peptide PKI-(6-22)-amide. Peptides containing the spatial conformation analogs D-phenylalanine, homophenylalanine, or phenylglycine were 60-120-fold less potent than the parent peptide. Peptides containing various para-substituted phenylalanines at position 10 were only 5-11-fold less potent. One exception to this was (4'-azidophenylalanine 10)PKI-(6-22)-amide, which was nearly equipotent with the parent inhibitor. The most potent analogs were those peptides containing highly aromatic residues at position 10. The 2'-thienylalanine 10, tryptophan (formyl) 10, tryptophan 10, and the 1'-naphthylalanine 10 analogs were 3-fold less potent, equipotent, slightly more potent, and 4-fold more potent than the parent peptide inhibitor, respectively. We conclude that phenylalanine 10 in PKI-(6-22)-amide, and presumably in the native protein inhibitor, interacts through specific hydrophobic and/or aromatic binding to a hydrophobic pocket or cleft near the active site of the protein kinase.

Amino Acid Sequence↗
PubMed1985

Identification of a trpG-related glutamine amide transfer domain in Escherichia coli GMP synthetase.

An improved method was developed to align related protein sequences and search for homology. A glutamine amide transfer domain was identified in an NH2-terminal segment of GMP synthetase from Escherichia coli. Amino acid residues 1-198 in GMP synthetase are homologous with the glutamine amide transfer domain in trpG X D-encoded anthranilate synthase component II-anthranilate phosphoribosyltransferase and the related pabA-encoded p-aminobenzoate synthase component II. This result supports a model for gene fusion in which a trpG-related glutamine amide transfer domain was recruited to augment the function of a primitive NH3-dependent GMP synthetase. Sequence analyses emphasize that glutamine amide transfer domains are thus far found only at the NH2 terminus of fused proteins. Two rules are formulated to explain trpG and trpG-related fusions. (i) trpG and trpG-related genes must have translocated immediately up-stream of genes destined for fusion in order to position a glutamine amide transfer domain at the NH2 terminus after fusion. (ii) trpG and trpG-related genes could not translocate adjacent to a regulatory region at the 5' end of an operon. These rules explain known trpG-like fusions and explain why trpG and pabA are not fused to trpE and pabB, respectively. Alignment searches of GMP synthetase with two other enzymes that bind GMP, E. coli amidophosphoribosyltransferase and human hypoxanthine-guanine phosphoribosyltransferase, suggest a structurally homologous segment which may constitute a GMP binding site.

Amidophosphoribosyltransferase↗
PubMed1986

Post-translational processing in Xenopus oocytes includes carboxyl-terminal amidation.

Xenopus oocytes are versatile cells capable of carrying out many post-translational processes. Although previously reported not to be capable of C-terminal amidation, this report demonstrates that Xenopus oocytes do indeed have an amidating enzyme. The amidating activity from Xenopus ovaries is compared to the known amidating activity found in porcine pituitaries. The demonstration of C-terminal amidation by Xenopus oocytes extends their usefulness in studying post-translational events.

Amidohydrolases↗