Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Many bioactive peptides terminate with an amino acid alpha-amide at their COOH terminus. The enzyme responsible for this essential posttranslational modification is known as peptidyl-glycine alpha-amidating monooxygenase or PAM. We identified cDNAs encoding the enzyme by using antibodies to screen a bovine intermediate pituitary lambda gt11 expression library. Antibodies to a beta-galactosidase/PAM fusion protein removed PAM activity from bovine pituitary homogenates. The 108,207 dalton protein predicted by the complete cDNA is approximately twice the size of purified PAM. An NH2-terminal signal sequence and short propeptide precede the NH2 terminus of purified PAM. The sequences of several PAM cyanogen bromide peptides were localized in the NH2-terminal half of the predicted protein. The cDNA encodes an additional 430 amino acid intragranular domain followed by a putative membrane spanning domain and a hydrophilic cytoplasmic domain. The forms of PAM purified from bovine neurointermediate pituitary may be generated by endoproteolytic cleavage at a subset of the 10 pairs of basic amino acids in the precursor. High levels of PAM mRNA were found in bovine pituitary and cerebral cortex. In corticotropic tumor cells, levels of PAM mRNA and pro-ACTH/endorphin mRNA were regulated in parallel by glucocorticoids and CRF.
Mol Endocrinol 1987 Nov
PMID:Structure of the precursor to an enzyme mediating COOH-terminal amidation in peptide biosynthesis. 315 62

Recent investigations have shown that the heart atrium is an endocrine tissue. In the present studies, high levels of peptidylglycine alpha-amidating monooxygenase (PAM), which catalyzes the formation of bioactive alpha-amidated peptides from their glycine-extended precursors, have been found in particulate fractions from bovine and rat heart atrium; only low levels of PAM activity were present in soluble fractions. Corresponding fractions from the ventricles contained 20-fold less activity. Immunocytochemical studies demonstrated that PAM was localized primarily to atrial cardiocytes, with a distribution resembling that of atriopeptin. Following differential centrifugation of rat atrial homogenates, most of the PAM activity was associated with crude granule fractions, with lesser amounts of activity associated with crude microsomal fractions. Upon further subcellular fractionation, PAM activity in the rat atrium was found primarily with immunoactive atriopeptin in fractions enriched in secretory granules. Following sodium dodecyl sulfate-polyacrylamide gel electrophoresis, antisera to purified bovine pituitary PAM identified a 113,000-dalton protein in bovine atrial microsomes and secretory granules; the protein predicted from the sequence of the cDNA encoding bovine pituitary PAM is of similar size (Eipper, B. A., Park, L. P., Dickerson, I. M., Keutmann, H. T., Thiele, E. A., Rodriguez, H., Schofield, P. R., and Mains, R. E. (1987) Mol. Endocrinol. 1, 777-790). Northern blot analysis using cDNA probes encoding bovine pituitary PAM demonstrated higher levels of PAM mRNA in heart atrium than in anterior pituitary. Rat heart contains PAM mRNA species of 3.6 and 3.8 kilobases, the smaller mRNA species corresponding in size to the PAM mRNA expressed in rat anterior pituitary.
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PMID:Membrane-associated peptidylglycine alpha-amidating monooxygenase in the heart. 337 31

The internal consistency of the PAM matrix model of protein evolution is here investigated. The 1 PAM matrix has been constructed from amino acid replacements observed in closely related sequences. Such replacements are of two types, those that do not require an intermediate amino acid replacement and those that do. The second type of replacement must generally be produced by a repetition of the first. This allows data on the first type to be used in predicting data on the second type so that some elements of the 1 PAM matrix may be used to predict others. A discrepancy of more than two orders of magnitude is found between the predictions and the data when this is carried out. This is partly accounted for by an error in constructing the matrix. However, it also seems necessary that the basic model be modified. Several possibilities are considered. One of these is to incorporate a site-dependent spectrum of mutabilities associated with each amino acid.
Mol Biol Evol 1985 Sep
PMID:On the PAM matrix model of protein evolution. 387 Aug 70

Kimura mistook ambiguous maximum parsimony codons for wrong codons. The maximum parsimony method performed well as judged by the two classes of serine codons (which can not be connected by silent mutations) on comparing the parsimony codons for serines in human, rabbit, and mouse alpha hemoglobin chains to actual codons determined by nucleotide sequencing. In genealogical reconstructions involving 247 eucaryotic globins, the maximum parsimony distances separating the contemporary sequences show that Kimura's Poisson and Dayhoff's PAM estimates of rate of globin evolution miss most of the superimposed replacements and are therefore seriously in error. Nor is Kimura's constant rate assumption and his belief in a single origin of myoglobin supported. Lamprey myoglobin appears to be most like lamprey hemoglobin, while gnathostome myoglobin seems closest to gnathostome hemoglobin. It was found that the three types of gnathostome globins (Mb, alpha Hb, beta Hb) evolved between the shark-boney vertebrate and bird-mammal ancestors at a much faster rate than from the latter ancestor to the present. The data indicate that rates were exceedingly fast during the origin of these globin chains because a high proportion of substitutions were adaptive. It was concluded that wherever strong stabilizing selection acts on a protein, somewhere in the past positive Darwinian selection must have spread the amino acid substitutions now being preserved.
J Mol Evol 1981
PMID:Globin evolution was apparently very rapid in early vertebrates: a reasonable case against the rate-constancy hypothesis. 725 36

To explore the molecular basis of the biochemical differences among acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and their alternative splicing and allelic variants, we investigated the acylation phase of cholinesterase catalysis, using phosphorylation as an analogous reaction. Rate constants for organophosphate (DFP) inactivation, as well as for oxime (PAM)-promoted reactivation, were calculated for antibody-immobilized human cholinesterases produced in Xenopus oocytes from natural and site-directed variants of the corresponding DNA constructs. BuChE displayed inactivation and reactivation rates 200- and 25-fold higher than either product of 3'-variable AChE DNAs, consistent with a putative in vivo function for BuChE as a detoxifier that protects AChE from inactivation. Chimeric substitution of active site gorge-lining residues in BuChE with the more anionic and aromatic residues of AChE, reduced inactivation 60-fold but reactivation only 4-fold, and the rate-limiting step of its catalysis appeared to be deacylation. In contrast, a positive charge at the acyl-binding site of BuChE decreased inactivation 8-fold and reactivation 30-fold. Finally, substitution of Asp70 by glycine, as in the natural 'atypical' BuChE variant, did not change the inactivation rate yet reduced reactivation 4-fold. Thus, a combination of electrostatic active site charges with aromatic residue differences at the gorge lining can explain the biochemical distinction between AChE and BuChE. Also, gorge-lining residues, including Asp70, appear to affect the deacylation step of catalysis by BuChE. Individuals carrying the 'atypical' BuChE allele may hence be unresponsive to oxime reactivation therapy following organophosphate poisoning.
Brain Res Mol Brain Res 1995 Jul
PMID:Successive organophosphate inhibition and oxime reactivation reveals distinct responses of recombinant human cholinesterase variants. 747 18

A highly conserved ten amino acid proregion separates the peptidylglycine alpha-hydroxylating monooxygenase (PHM) domain of the bifunctional peptidylglycine alpha-amidating monooxygenase (PAM) protein from the NH2-terminal signal peptide; propeptides with amino acid sequences similar to the PAM proregion have been identified in other secreted proteins. In AtT-20 cells, but not in human embryonic kidney (hEK)-293 cells, an endogenous endoprotease acting at a site distal to the trans-Golgi network efficiently removes the propeptide from stably transfected monofunctional PHM (PHMs). We constructed a mutant PHM protein (delta ProPHMs) in which the proregion was deleted and the signal peptide joined directly to the monooxygenase domain. Newly synthesized, enzymatically active delta ProPHMs was secreted from both AtT-20 cells and hEK-293 cells more slowly than PHMs. In endocrine cells, the proregion was not required for storage in regulated secretory granules. We transferred the PAM proregion to prohormone convertase 2 (PC2), another soluble constituent of secretory granules, to determine whether the effect of the proregion were transferrable. In both AtT-20 cells and hEK-293 cells, the PAM/PC2 fusion molecule was able to exit the endoplasmic reticulum more rapidly than PC2.
Mol Endocrinol 1995 Jan
PMID:The NH2-terminal proregion of peptidylglycine alpha-amidating monooxygenase facilitates the secretion of soluble proteins. 776 Aug 48

The final two steps in the biosynthesis of alpha-amidated bioactive peptides are catalyzed by peptidylglycine alpha-hydroxylating monooxygenase (PHM; EC 1.14.17.3) and peptidyl-alpha-hydroxyglycine alpha-amidating lyase (PAL; EC 4.3.2.5). These enzymes are derived from the bifunctional precursor protein, peptidylglycine alpha-amidating monooxygenase. Because PHM is rate-limiting in peptide amidation and is copper-dependent, we examined the consequences of in vivo treatments with the copper-chelating drug disulfiram (Antabuse) on levels of alpha-amidated peptides and expression of PHM and PAL. Decreases in two amidated peptides (alpha-melanotropin and cholecystokinin) after disulfiram treatment were extremely pronounced outside the blood-brain barrier, with moderate decreases in the central nervous system. Unexpectedly, when assayed under optimal conditions in vitro, PHM activity was increased by disulfiram treatment, whereas PAL activity was unaltered. The increase in PHM activity in pituitary and atrium occurred within a few hours after the start of disulfiram treatment and was sustained up to 2 weeks after the cessation of treatment, whereas levels of alpha-amidated peptides remained low. Northern and Western blot analyses demonstrated that disulfiram had no influence on levels of peptidylglycine alpha-amidating monooxygenase mRNA or protein. Thus, inhibition of alpha-amidation by disulfiram in vivo occurs despite an increased Vmax of PHM assayed in vitro. The increase in PHM activity may result from induction of a physiologic mechanism that normally regulates this rate-limiting enzyme.
Mol Pharmacol 1993 Nov
PMID:Peptide alpha-amidation and peptidylglycine alpha-hydroxylating monooxygenase: control by disulfiram. 824 21

Expression of the beta 2-microglobulin (beta 2-m) and major histocompatibility complex (MHC) class I genes is coordinately regulated. By ligation-mediated polymerase chain reaction, we have analyzed in vivo factor binding to the promoter region of the murine beta 2-m gene. In adult spleen, in which beta 2-m is expressed, strong protection was found in three elements. Two of these elements, the beta 2-m NF-kappa B binding site and the interferon consensus sequence, are homologous to the regulatory elements of the MHC class I genes and were also found to be protected in spleen. A third protected element, PAM, identified in this work, is unique to the beta 2-m gene. None of the elements showed protection in brain tissue, in which neither the beta 2-m nor the MHC class I gene is expressed. In vivo footprinting was also performed with F9 embryonal carcinoma cells, in which expression of the beta 2-m and MHC class I genes is induced at a low level only upon stimulation with retinoic acid (RA). No in vivo protection was detected before and after RA treatment of F9 cells, indicating that RA induction of beta 2-m (and MHC class I) expression occurs without detectable in vivo factor occupancy, whereas EL4 T lymphocytes expressing beta 2-m at a high level exhibited strong protection similar to that in spleen. Despite the lack of in vivo occupancy, the nuclear factors specific for each of the three elements were present in brain tissue and F9 cells as well as in spleen tissue and EL4 cells. We show that PAM, an element identified by its in vivo protection, binds nuclear factors ranging from 40 to 50 kDa in size and is capable of enhancing transcription of a reporter in F9 and other cells. Taken together, these results indicate that in vivo factor occupancy for the beta 2-m and MHC class I promoters is coordinated and occurs through a mechanism other than mere expression of relevant factors.
Mol Cell Biol 1993 Nov
PMID:A regulatory element in the beta 2-microglobulin promoter identified by in vivo footprinting. 841 59

The exhaustive matching of the protein sequence database makes possible a broadly based study of insertions and deletions (indels) during divergent evolution. In this study, the probability of a gap in an alignment of a pair of homologous protein sequences was found to increase with the evolutionary distance measured in PAM units (number of accepted point mutations per 100 amino acid residues). A relationship between the average number of amino acid residues between indels and evolutionary distance suggests that a unit 30 to 40 amino acid residues in length remains, on average, undisrupted by indels during divergent evolution. Further, the probability of a gap was found to be inversely proportional to gap length raised to the 1.7 power. This empirical law fits closely over the entire range of gap lengths examined. Gap length distribution is largely independent of evolutionary distance. These results rule out the widely used linear gap penalty as a satisfactory formula for scoring gaps when constructing alignments. Further, the observed gap length distribution can be explained by a simple model of selective pressures governing the acceptance of indels during divergent evolution. Finally, this model provides theoretical support for using indels as part of "parsing algorithms", important in the de novo prediction of the folded structure of proteins from the sequence data.
J Mol Biol 1993 Feb 20
PMID:Empirical and structural models for insertions and deletions in the divergent evolution of proteins. 844 36

Sequences of 1,862 chromosomally encoded Escherichia coli K12 proteins were examined to identify genes likely to have arisen by duplication of genes in an ancestral chromosome. The criteria for sequence relatedness were an alignment of at least 100 amino acid residues and a PAM distance (number of accepted point mutations per 100 residues separating two sequences) below 250. A total of 971 of the 1,862 proteins examined were found in 2,329 sequence-related pairs that met these criteria. Most proteins of the sequence-related pairs were related in cellular function, as judged by biochemical and/or physiological features. Many of the pairs of proteins could be grouped into sequence-related families. If such groupings were generated from ancestral genes by duplication and divergence events, through these sequence comparisons we can identify putative ancestral sequences of the present-day genes of E. coli and other organisms. The results suggest that the 971 paralogous genes could have been derived from only 204 ancestral genes. We have also shown that the process of duplication and divergence is not the exclusive mechanism of evolution of all E. coli genes. Indeed, the relationships among the sequences of multiple (in the sense of redundant) enzymes indicate that nearly half could have arisen either by convergent evolution or by lateral transfer. Therefore, not all functionally related genes need arise by duplication and divergence.
Mol Biol Evol 1995 Nov
PMID:Gene products of Escherichia coli: sequence comparisons and common ancestries. 852 50


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