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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The prn gene cluster involved in L-proline catabolism in Aspergillus nidulans, has the gene order prnA-prnD-regulatory region-prnB-prnC. prnB, prnD, and prnC specify proline permease, proline oxidase, and delta1-pyrroline-5-carboxylate (P5C) dehydrogenase, respectively. prnA is probably a positive regulatory gene whose product is necessary for expression of the prn activities. Proline induces proline permease and P5C dehydrogenase in prnD- mutants which lack proline oxidase, showing that proline does not have to be converted to P5C to act as inducer. Deletion mutations extending from within prnD to within prnB result in considerably reduced expression of prnC, whereas a prnD- prnB- double mutant shows normal prnC expression. This strongly suggests that the deletion mutations eliminate a promotor/initiator site for transcription of a dicistronic messenger for prnB and prnC. The fact that the deletions do not eliminate prnC expression altogether indicates that at least one other species of prnC transcript (monocistronic, tricistronic, or tetracistronic) can be made.
Mol Gen Genet 1978 Jul 06
PMID:Reduced expression of a distal gene of the prn gene cluster in deletion mutants of Aspergillus nidulans: genetic evidence for a dicistronic messenger in an eukaryote. 35 39

The receptor binding surface of human follicle-stimulating hormone (hFSH) is mimicked by synthetic peptides corresponding to the hFSH-beta chain amino acid sequences 33-53 [Santa-Coloma, T. A., Dattatreyamurty, D., and Reichert, L. E., Jr. (1990), Biochemistry 29, 1194-1200], 81-95 [Santa-Coloma, T. A., Reichert, L. E., Jr. (1990), J. Biol. Chem. 265, 5037-5042], and the combined sequence (33-53)-(81-95) [Santa-Coloma, T. A., Crabb, J. W., and Reichert, L. E., Jr. (1991), Mol. Cell. Endocrinol. 78, 197-204]. These peptides have been shown to inhibit binding of hFSH to its receptor. Circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy were used to determine the structure of the first peptide in this series, the 21 amino acid peptide hFSH-beta-(33-53), H2N-YTRDLVYKDPARPKIQKTCTF-COOH. Analysis of CD data indicated the presence of approximately equal amounts of antiparallel beta-pleated sheet, turns including a beta-turn, "other" structures, and a small amount of alpha-helix. The major characteristics of the structure were found to be relatively stable at acidic pH and the predominant effect of increased solvent polarity was a small increase in alpha-helical content. One- and two-dimensional NMR techniques were used to obtain full proton and carbon signal assignments in aqueous solution at pH 3.1. Analysis of NMR results confirmed the presence of the structural features revealed by CD analysis and provided a detailed picture of the secondary structural elements and global folding pattern in hFSH-beta-(33-53). These features included an antiparallel beta-sheet (residues 38-51 and 46-48), turns within residues 41-46, and 50-52 (a beta-turn) and a small N-terminal helical region comprised of amino acids 34-36. One of the turns is facilitated by prolines 42 and 45. Proline-45 was constrained to the trans conformation, whereas proline-42 favored the trans conformer (approximately 70%) over the cis (approximately 30%). Two resonances were observed for the single alanine residue (A-43) sequentially proximal to P-42, but the rest of the structure was minimally affected by the isomerization at proline-42. The major population of molecules, containing trans-42 and trans-45 prolines, presented 120 NOEs. Distance geometry calculations with 140 distance constraints and energy minimization refinements were used to derive a moderately well-defined model of the peptide's structure.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Solution structure of a synthetic peptide corresponding to a receptor binding region of FSH (hFSH-beta 33-53). 144 99

In a set of proteins studied at high resolution by X-ray crystallography over a half of all cis and trans-proline residues could be unambiguously assigned to one of the two forms of pyrrolidine ring puckering, called UP and DOWN. Of these, 89% of the cis-proline residues exhibit the DOWN pucker, while the trans-proline residues, on average, are about evenly distributed between the two forms. Of trans-proline residues found in alpha-helices, 79% have the UP ring pucker. trans-proline residues occurring in other situations are more equally distributed between the two forms of pucker, although further generalizations may be possible. Proline residues in a set of crystal structures of short polypeptides were also examined. As in the protein sample, a tendency for the cis-proline residues to have the DOWN pucker was observed, but the effect was less pronounced.
J Mol Biol 1992 Dec 05
PMID:Pyrrolidine ring puckering in cis and trans-proline residues in proteins and polypeptides. Different puckers are favoured in certain situations. 146 11

Thyrotropin-Releasing hormone (TRH)-degrading pyroglutamyl peptidase I (PGP I) and prolylendopeptidase (PE) activities have been demonstrated in rat insulinoma RINm 5F cell line. These two enzymes catalyze the conversion of TRH to Histydyl-Proline-Diketopiperazine and to acid TRH respectively. After cell fractionation, we found all the PGP I and PE activities in the cytosolic fraction. The membrane-bound PGP II activity is not detectable in the RINm 5F cells. Further investigations on these two cytosolic enzymes show that pyroglutamyl- and proline-containing peptides are inhibitors of each TRH-degrading enzyme. Gel filtration chromatography on Sephadex G100 shows that PGP I and PE activity have an apparent molecular mass of about 18 kDa and 57 kDa, respectively. Kinetic analysis with TRH as substrate, gives a Km of 44 microM and 235 microM, and a Vmax of 1.49 and 8.80 pmol/min/micrograms protein for PGP I and PE, respectively. Immunoreactive TRH, His-Pro-Diketopiperazine and acid TRH levels in the cell line extracts are 2.2 +/- 0.9, 22.5 +/- 11.1 and 28.7 +/- 14.6 pg/1O6 cells, respectively. When cells have been incubated for 2 to 72 hours with a P.E. inhibitor (Z-Gly-Pro-CHN2) at 5 x 10(-7) M, both cell PGP I and PE activities are inhibited. No change in the cellular content of immunoreactive TRH, His-Pro-Diketopiperazine and acid TRH have been observed in treated cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem 1991 Jul 24
PMID:Evidence for pyroglutamyl peptidase I and prolyl endopeptidase activities in the rat insulinoma cell line RINm 5F: lack of relationship with TRH metabolism. 168 21

Integral membrane proteins often contain proline residues in their presumably alpha-helical transmembrane segments. This is in marked contrast to globular proteins, where proline is rarely found inside alpha-helices. Proline residues cause kinks in helices, and, in addition to leaving the i-4 backbone carbonyl without its normal hydrogen bond donor, also sterically prevent the (i-3)-carbonyl-(i + l)-amide backbone hydrogen bond from forming. Here, some structural aspects of proline kinks in transmembrane helices are discussed on the basis of an analysis of Pro-kinked helices in the photosynthetic reaction center and bacteriorhodopsin, as well as results from an analysis of Pro-containing transmembrane segments identified in the NBRF Protein Sequence Databank.
J Mol Biol 1991 Apr 05
PMID:Proline kinks in transmembrane alpha-helices. 201 41

Proline-rich proteins (PRPs) constitute a group of unusual salivary proteins encoded by tissue-specific multigene families which can be dramatically induced (20- to 70-fold) in vivo in rats, mice and hamsters by treatment with the beta-agonist isoproterenol. Addition of dibutyryl cyclic AMP (dbcAMP) or forskolin to hamster parotid gland primary cultures resulted in a large increase (15- to 30-fold) in PRP mRNA levels. The same time-course and levels of induction of PRP mRNA by dbcAMP and isoproterenol were found in primary cultures, indicating that both effectors act through the same mechanism. Induction by isoproterenol, but not by dbcAMP or forskolin, was blocked by the beta-antagonist propranolol. Incorporation of [3H]proline into PRPs was stimulated in primary cultures by all three effectors. The greatest increase in proline incorporation was in the [3H]PRPs recovered in the culture medium of induced cells. These studies demonstrate that cAMP or agents which increase intracellular cAMP levels increase PRP gene expression in primary cultures of parotid glands. Pretreatment of the cells with cycloheximide blocked the induction of PRP mRNAs which indicates that the synthesis of a trans-acting factor may be necessary for transcriptional activation of the PRP genes. alpha-Amylase mRNA, another tissue-specific gene product, was not significantly affected by cycloheximide treatment.
J Mol Endocrinol 1990 Feb
PMID:Regulation of proline-rich protein gene expression by cyclic AMP in primary cultures of hamster parotid glands. 215 54

Proline lacks an amide proton when found within proteins. This precludes hydrogen bonding between it and hydrogen bond acceptors, and thus often restricts the residue to the first four positions of an alpha-helix. Helices with proline after position four have a pronounced kink [(1988) J. Mol. Biol. 203, 601-619]. In these cases, we find that the proline residue almost almost always occurs on the solvent exposed face of each helix. This positioning facilitates the compensatory hydrogen bonding between solvent and residues P-3 and P-4 (relative to proline, P), through the formation of the kink. Further, it aids in the packing of long helical structures around globular protein structures.
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PMID:The influence of proline residues on alpha-helical structure. 226 52

Proline independence in CHO-K1 Chinese hamster cells has in previous studies been characterized as an auxotrophic gene mutation. In the absence of direct proof, an alternative model must be considered, based on suppression of proline synthesis by DNA methylation changes at one or more loci concerned. This concept receives strong support from the present study, in which we show that treatment of CHO-K1 cells with 5-azacytidine induces a 10(5)-10(6) increase in background conversion to the proline-independent state. Revertants thus obtained, as well as those arising spontaneously or after treatment with ethyl methane sulfonate, are stable phenotypically in the presence or absence of proline. Proline independence in all variants examined was correlated with increased activity of pyrroline-5-carboxylate synthase. Four of five variants induced with 5-azacytidine showed simultaneous increases in activity of ornithine aminotransferase as well. Our data suggest that epigenetic, rather than genetic changes, underlie the transitions between proline dependence and independence in CHO-K1 cells.
Somat Cell Mol Genet 1984 Nov
PMID:High-frequency induction by 5-azacytidine of proline independence in CHO-K1 cells. 620 9

Proline-rich proteins are major components of parotid and submandibular saliva in humans as well as other animals. They can be divided into acidic, basic and glycosylated proteins. The primary structure of the acidic proline-rich proteins is unique and shows that the proteins do not belong to any known family of proteins. The proline-rich proteins are apparently synthesized the acinar cells of the salivary glands and their phenotypic expression is under complex genetic control. The acidic proline-rich proteins will bind calcium with a strength which indicates that they may be important in maintaining the concentration of ionic calcium in saliva. Moreover they can inhibit formation of hydroxyapatite, whereby growth of hydroxyapatite crystals on the tooth surface in vivo may be avoided. Both of these activities as well as the binding site for hydroxyapatite are located in the N-terminal proline-poor part of the protein. Little is known about the functions of the glycosylated and basic proline-rich proteins.
Mol Cell Biochem 1982 Jun 11
PMID:Salivary proline-rich proteins. 681 92

We determined the amino acid and radiolabel sequences of tryptic [32P]phosphopeptides of the purified human estrogen receptor (hER) from MCF-7 cells and Sf9 cells. Serine 118 was identified as a site that was phosphorylated independently of estradiol-binding in MCF-7 cells. Proline is on the carboxy terminus of serine 118, which suggests that the serine-proline may be a consensus phosphorylation site motif for either the mitogen-activated protein (MAP) kinase or p34cdc2 kinase. MAP kinase selectively phosphorylated the recombinant hER in vitro on serine 118 independent of estradiol-binding, whereas p34cdc2 did not phosphorylate the hER. We demonstrated previously that serine 167 of the hER was phosphorylated in an estradiol-dependent manner. We therefore compared the consequence of hER phosphorylation at serine 118 by MAP kinase and phosphorylation at serine 167 by casein kinase II on the receptor's affinity for specific DNA binding. The binding of the hER to an estrogen response element was not altered by phosphorylation with MAP kinase at serine 118 but was significantly increased when phosphorylated at serine 167 by casein kinase II. These data suggest that phosphorylation of the hER by MAP kinase(s) pathways may influence receptor action by a mechanism other than the estradiol-dependent phosphorylation of hER by casein kinase II.
J Steroid Biochem Mol Biol 1995 Nov
PMID:Phosphorylation of the human estrogen receptor by mitogen-activated protein kinase and casein kinase II: consequence on DNA binding. 749 95


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