排序方式: 共有37条查询结果,搜索用时 171 毫秒
1.
Substitution of 5-nitro-
-histidine for
-histidine is proposed as a useful tool to study the relationships among tautomerism, acid-base properties, and biological activity of peptide hormones. This approach is illustrated by an analog of the tripeptide thyroliberin, [5-nitro-
-histidine]2-thyroliberin, which has been prepared by solid-phase peptide synthesis. The acid-base properties of the hormone analog and the position of the imidazole ring tautomeric equilibrium have been investigated by spectroscopic methods. Correlation of these properties with the biological activity of the nitrated tripeptide strongly supports the idea that imidazole ring tautomerism is a key factor for hormonal activity and that the Nτ-H tautomer must be considered the biologically active form of thyroliberin. 相似文献
2.
3.
Two Structural Domains Mediate Two Sequential Events in [gamma]-Zein Targeting: Protein Endoplasmic Reticulum Retention and Protein Body Formation 总被引:3,自引:2,他引:1 下载免费PDF全文
[gamma]-Zein is a maize storage protein synthesized by endosperm cells and stored together with [alpha]- and [beta]-zeins in specialized organelles called protein bodies. Previous studies have shown that in maize there is only one type of protein body and it is derived directly from the endoplasmic reticulum (ER). In this article, we describe the domains of [gamma]-zein involved in ER retention and the domains involved in protein body formation. To identify the signal responsible for [gamma]-zein retention in ER-derived protein bodies, DNAs encoding various deletion mutants of [gamma]-zein were constructed and introduced into Arabidopsis as a heterologous system. By using pulse-chase experiments and immunoelectron microscopy, we demonstrated that the deletion of a proline-rich domain at the N terminus of [gamma]-zein puts an end to its retention in the ER; this resulted in the secretion of the mutated protein. The amino acid sequence of [gamma]-zein necessary for ER retention is the repeat domain composed of eight units of the hexapeptide PPPVHL. In addition, we observed that only those [gamma]-zein mutants that contained both the proline-rich repeat domain and the C-terminal cysteine-rich domain were able to form ER-derived protein bodies. We suggest that the retention of [gamma]-zein in the ER could be a result of a protein-protein association or a transient interaction of the repeat domain with ER membranes. 相似文献
4.
Gruber Véronique Berna Patrick P. Arnaud Thierry Bournat Philippe Clément Christèle Mison Dominique Olagnier Béatrice Philippe Laurence Theisen Manfred Baudino Sylvie Bénicourt Claude Cudrey Claire Bloës Carole Duchateau Nathalie Dufour Sylvie Gueguen Catherine Jacquet Séverine Ollivo Catherine Poncetta Christine Zorn Nathalie Ludevid Dolores Van Dorsselaer Alain Verger Robert Doherty Annette Mérot Bertrand Danzin Charles 《Molecular breeding : new strategies in plant improvement》2001,7(4):329-340
A recombinant dog gastric lipase with therapeutic potential for the treatment of exocrine pancreatic insufficiency was expressed in transgenic tobacco plants. We targeted the protein using two different signal sequences for either vacuolar retention or secretion. In both cases, an active glycosylated recombinant protein was obtained. The recombinant enzymes and the native enzyme displayed similar properties including acid resistance and acidic optimum pH. The proteolytic maturation and the specific activity of the recombinant proteins, however, were found to be dependent on subcellular compartmentalization. Expression levels of recombinant dog gastric lipase were about 5% and 7% of acid extractable plant proteins for vacuolar retention and secretion respectively. This expression system already has allowed the production of tens of grams of purified lipase through open-field culture of transgenic tobacco plants. 相似文献
5.
Margarita Torrent Blanca Llompart Sabine Lasserre-Ramassamy Immaculada Llop-Tous Miriam Bastida Pau Marzabal Ann Westerholm-Parvinen Markku Saloheimo Peter B Heifetz M Dolors Ludevid 《BMC biology》2009,7(1):5-14
Background
Protein bodies (PBs) are natural endoplasmic reticulum (ER) or vacuole plant-derived organelles that stably accumulate large amounts of storage proteins in seeds. The proline-rich N-terminal domain derived from the maize storage protein γ zein (Zera) is sufficient to induce PBs in non-seed tissues of Arabidopsis and tobacco. This Zera property opens up new routes for high-level accumulation of recombinant proteins by fusion of Zera with proteins of interest. In this work we extend the advantageous properties of plant seed PBs to recombinant protein production in useful non-plant eukaryotic hosts including cultured fungal, mammalian and insect cells. 相似文献6.
M. Dolors Ludevid Luis Ruiz-Avila M. Pilar Vallés Virginia Stiefel Margarita Torrent Josep M. Torné Pere Puigdomènech 《Planta》1990,180(4):524-529
Hydroxyproline-rich glycoproteins (HRGPs) fromZea mays have been immunolocalized in the cell wall of root tip cells using ultrathin sections and antibodies ellicited against the
purified protein. The accumulation of mRNA corresponding to this protein was studied using the cDNA probe. Maximum accumulation
of the mRNA was found in tissues with a high proportion of dividing cells such as those in the root tip of young maize seedlings
and a close relationship with cellular division was also observed in in-vitro cultures. However, the level of the mRNA in
elongating tissues was minimal, as shown by studies carried out on the elongation zones of root tips and coleoptiles. The
mRNA was induced by stress conditions, particularly by wounding young leaves and coleoptiles. It is concluded that in maize
this group of proline-rich cell-wall proteins accumulates during cell division and not during cell elongation or differentiation,
and participates in the stress-response mechanisms of the plant. 相似文献
7.
8.
Storage proteins of maize (Zea mays L.) were studied in germinated seeds, as were the proteins of protein bodies isolated from endosperms at different germination
times. Major endosperm storage proteins were degraded in a sequential way, glutelin 2 being hydrolysed faster than zein 1.
Immunocytochemical labelling of the different protein bodies using the antisera anti-glutelin 2 and anti-zein 1 indicates
that the protein bodies were degraded by progressive hydrolysis from their surface. The digestion of glutelin 2 correlated
with the disappearance of the protein-body membranes. 相似文献
9.
A hydroxyproline-rich glycoprotein (HRGP) component of the maize cell wall was shown to be present in different organs of the plant by extraction of cell wall proteins and detection by Western blotting and immunocytochemistry. Antibodies raised against the protein or against synthetic peptides designed from the protein sequence immunoprecipitated a proline-rich polypeptide which was synthesized in-vitro from poly(A) + RNA extracted from different tissues of the plant and from the complete in-vitro-transcribed mRNA. A very low amount of the protein was found in immature embryos. In particular, the protein could not be detected in the scutellum either by Western blotting or by immunocytochemistry. In agreement with this finding, HRGP mRNA was barely detected in the scutellum, in contrast to its accumulation in the embryo axis. Our results indicate the existence of a unique cell wall structure in embryonic tissues from maize as well as a tissuespecific component of the control of maize HRGP gene expression, distinct to others already described such as cell division.Abbreviations HRGP(s)
hydroxyproline-richglycoprotein(s)
- DAP
days after pollination
The present work was supported by grants from Plan Nacional de Investigation Cientifica y Técnica (grant BI088-0242) and European Communities (grant BAP-374). L.R.-A. is the recipient of a fellowship from the Plan Nacional de Formación de Personal Investigador. 相似文献
10.
Expression of a maize cell wall hydroxyproline-rich glycoprotein gene in early leaf and root vascular differentiation. 总被引:15,自引:7,他引:8 下载免费PDF全文
V Stiefel L Ruiz-Avila R Raz M Pilar Valls J Gmez M Pags J A Martínez-Izquierdo M D Ludevid J A Langdale T Nelson 《The Plant cell》1990,2(8):785-793
The spatial pattern of expression for a maize gene encoding a hydroxyproline-rich glycoprotein (HRGP) was determined by in situ hybridization. During normal development of roots and leaves, the expression of the gene was transient and particularly high in regions initiating vascular elements and associated sclerenchyma. Its expression was also associated with the differentiation of vascular elements in a variety of other tissues. The gene encoded an HRGP that had been extracted from the cell walls of maize suspension culture cells and several other embryonic and post-embryonic tissues. The gene was present in one or two copies in different varieties of maize and in the related monocots teosinte and sorghum. A single gene was cloned from maize using a previously characterized HRGP cDNA clone [Stiefel et al. (1988). Plant Mol. Biol. 11, 483-493]. In addition to the coding sequences for the HRGP and an N-terminal signal sequence, the gene contained a single intron in the nontranslated 3' end. 相似文献