共查询到20条相似文献,搜索用时 15 毫秒
1.
Summary Proteolytic enzymes play a key role in a variety of physiological processes in which the degradation of macromolecules is essential: angiogenesis, embryogenesis, bone and tissue remodelling, blood hemostasis and cell migration. The action of these enzymes is also crucial in the development of many pathological conditions such as wound healing, neoplasia, inflammation and arthritic disorders.the activity of proteases is negatively affected by specific protease-inhibitors. Various growth factors and other cytokines modulate the synthesis and secretion of both proteases and protease-inhibitors. The study of this regulation results in a better insight into (patho)physiology at the molecular level and promises to result in alternative treatment strategies. 相似文献
2.
Proteins sequestered by a non-selective bulk process within the lysosomes turn over with an apparent half-life of about 8 minutes and this rapid lysosomal proteolysis is initiated by endopeptidases, in particular by the cathepsins D and L. We describe also the cathepsins B and H which show mainly exopeptidase and only low endopeptidase activity. Especially cathepsin H is most probably the only lysosomal aminopeptidase in many cell types. Additionally, the properties of other mammalian lysosomal endo- and exopeptidases are compared. Finally, we discuss some of the conditions for the action of lysosomal proteases as the low intralysosomal pH, the high part of lysosomal thiol groups and the absence of intralysosomal proteinase inhibitors. 相似文献
3.
Autophagy and lysosomal proteolysis in the liver 总被引:1,自引:0,他引:1
B Grinde 《Experientia》1985,41(9):1089-1095
Autophagy is defined as any process whereby cellular macromolecules destined for degradation gain access to the lysosomes. A review is presented on the physiological significance, mechanisms and regulation of autophagy in hepatocytes, concentrating on the issue of regulation. The article ends by discussing techniques available for future research. 相似文献
4.
B. Grinde 《Cellular and molecular life sciences : CMLS》1985,41(9):1089-1095
Summary Autophagy is defined as any process whereby cellular macromolecules destined for degradation gain access to the lysosomes. A review is presented on the physiological significance, mechanisms and regulation of autophagy in hepatocytes, concentrating on the issue of regulation. The article ends by discussing techniques available for future research. 相似文献
5.
Proteases and proteolysis in the lysosome. 总被引:6,自引:0,他引:6
Proteins sequestered by a non-selective bulk process within the lysosomes turn over with an apparent half-life of about 8 minutes and this rapid lysosomal proteolysis is initiated by endopeptidases, in particular by the cathepsins D and L. We describe also the cathepsins B and H which show mainly exopeptidase and only low endopeptidase activity. Especially cathepsin H is most probably the only lysosomal aminopeptidase in many cell types. Additionally, the properties of other mammalian lysosomal endo- and exopeptidases are compared. Finally, we discuss some of the conditions for the action of lysosomal proteases as the low intralysosomal pH, the high part of lysosomal thiol groups and the absence of intralysosomal proteinase inhibitors. 相似文献
6.
S. R. Terlecky 《Cellular and molecular life sciences : CMLS》1994,50(11-12):1021-1025
Confluent cultured cells activate a lysosomal pathway of polypeptide breakdown in response to withdrawal of serum growth factors. The substrates for this proteolytic pathway are a restricted class of cytosolic polypeptides containing peptide sequences biochemically related to lysine-phenylalanine-glutamate-arginine-glutamine, or, in single amino acid abbreviations, KFERQ. The heat shock cognate protein of 73 kD (hsc73) binds to a variety of polypeptides via this molecular determinant and facilitates their lysosomal import and degradation. In addition, a portion of intracellular hsc73 resides within the lysosome and appears to be an essential component of the proteolytic machinery. Several potential mechanisms by which hsc73 mediates selective lysosomal import and degradation of polypeptides are discussed. 相似文献
7.
R. Shringarpure T. Grune K.J.A. Davies 《Cellular and molecular life sciences : CMLS》2001,58(10):1442-1450
The generation of reactive oxygen species is an inevitable aspect of aerobic life. In addition to being exposed to free radicals in the environment, aerobic organisms must also deal with oxygen radicals generated as byproducts of a number of physiological mechanisms - for example, by the mitochondrial and endoplasmic reticulum electron transport chains, and by cells of the immune system. Although most organisms are equipped with several lines of defense against oxidative stress, these defensive mechanisms are not 100% effective, and oxidatively modified forms of proteins accumulate during aging, and in many pathological conditions.?Oxidatively modified proteins can form large aggregates due to covalent cross-linking or increased surface hydrophobicity. Unless repaired or removed from cells, these oxidized proteins are often toxic and can threaten cell viability. Mammalian cells exhibit only limited direct repair mechanisms, and oxidatively damaged proteins appear to undergo selective proteolysis, primarily by the major cytosolic proteinase, the proteasome. Interestingly, it appears that the 20S 'core' proteasome conducts the recognition and elimination of oxidized proteins in an ATP-independent and ubiquitin-independent pathway. Received 31 May 2001; accepted 26 June 2001 相似文献
8.
Hypophysectomy increases both periosteal resorption and endosteal apposition along the femur diaphysis in rat. Administration of alpha-MSH decreased the periosteal resorption but had no effect on the endosteal apposition. ACTH had only minor effects on the endosteum. Thus, alpha-MSH and ACTH, in the doses used, have different effects on cortical bone in rat. The effect of alpha-MSH on cortical bone could be an effect of the hormone alone or by its stimulation of other factors. 相似文献
9.
10.
11.
R. S. Alphin J. A. Vocac D. A. Droppleman 《Cellular and molecular life sciences : CMLS》1972,28(1):53-54
Zusammenfassung Die Wirkung eines Lignolsulphonates auf die Pepsinproteolyse im Hund mit totaler Magenfistel wurde untersucht und geronnenes Eialbumin als Substrat der Pepsinverdauung verwendet. Es ergibt sich, dass der Pepsin-Inhibitor AHR-2438B-wie früher bei der Ratte nachgewiesen — auch beim Hund die Proteolyse im Magen wirksam hemmt. 相似文献
12.
D. Heinegård 《Cellular and molecular life sciences : CMLS》1995,51(3):195-196
Bone is one of the most dynamic tissues, with constant remodelling and repair of minor defects during the whole life cycle. These processes have key roles in replacing fatigued, non-functional tissue with fresh tissue which has the proper mechanical properties. In this process, a balance between breakdown of less functional tissue and new tissue production is a prerequisite for tissue integrity and function. One of the major health problems in the elderly, i.e. osteoporosis and ensuing bone fracture, is caused by an imbalance between breakdown and synthesis in this continuous bone remodelling. Thus the study of cellular and molecular events governing the relevant processes is a prerequisite for understanding mechanisms and for future efficient therapeutical intervention. 相似文献
13.
An in vitro demonstration of proteolysis by macrophages and its increase with coumarin 总被引:1,自引:0,他引:1
Zusammenfassung Es wird gezeigt, dass die normale proteolytische Tätigkeit von stimulierten peritonealen Makrophagen der Maus durch das Benzo-pyron-Cumarin in vitro beträchtlich erhöht wird.
We would like to thank Schaper and Brümmer KG, West Germany, for the coumarin, and the Australian Research Grants Committee for their support. 相似文献
We would like to thank Schaper and Brümmer KG, West Germany, for the coumarin, and the Australian Research Grants Committee for their support. 相似文献
14.
Résumé Partant de l'effet de la température sur la cinétique de la protéolyse peptique de l'ovalbumine native ou denaturée, on a estimé l'énergie d'activation, l'enthalpie et l'entropie de l'association enzyme-substrat. 相似文献
15.
A Hasilik 《Experientia》1992,48(2):130-151
Lysosomal enzymes are subjected to a number of modifications including carbohydrate restructuring and proteolytic maturation. Some of these reactions support lysosomal targeting, others are necessary for activation or keeping the enzyme inactive before being segregated, while still others may be adventitious. The non-segregated fraction of the enzyme is secreted and can be isolated from the medium. It is considered that the secreted lysosomal enzymes fulfill certain physiological and pathophysiological roles. By comparing the secreted and the intracellular enzymes it is possible to distinguish between the reactions that occur before and after the segregation. In this review the reactions that may influence the segregation are referred to as the early processing and those characteristic for the enzymes isolated from lysosomal compartments as the late processing. The early processing is characterized mainly by modifications of carbohydrate side chains. In the late processing, proteolytic fragmentation represents the most conspicuous changes. The review focuses on the compartmentation of the reactions and the proteolytic fragmentation of lysosomal enzyme precursors. While a plethora of proteolytic reactions are involved, our knowledge of the proteinases responsible for the particular maturation reactions remains very limited. The review points also to work with cells from patients affected with lysosomal storage disorders, which contributed to our understanding of the lysosomal apparatus. 相似文献
16.
Zusammenfassung Die Umwandlung von Tyrosin in Katecholamin wurde in verschiedenen Blutgefässen untersucht. Die Katecholamin-Biosynthese erfolgte am schnellsten in der Arteria mesenterica sup. (0,6 g/g/h), was zehnmal höher liegt als diejenige in der Aorta oder in der Arteria pulmonalis. 相似文献
17.
D. P. Murr 《Cellular and molecular life sciences : CMLS》1977,33(12):1559-1561
Summary A metabolic intermediate isolated from apple tissue fed either methionine or 5-methylthioadenosine has been tentatively identified as a methionine-pyridoxal Schiff base. The formation of this compound is discussed in relation to ethylene biosynthesis.Acknowledgments. This investigation was supported by Research Grant AO-150 from the National Research Council of Canada. 相似文献
18.
19.
Mechanical forces are increasingly recognized as central factors in the regulation of tissue morphogenesis and homeostasis. Central to the transduction of mechanical information into biochemical signaling is the contractile actomyosin cytoskeleton. Fluctuations in actomyosin contraction are sensed by tension sensitive systems at the interface between actomyosin and cell adhesion complexes. We review the current knowledge about the mechanical coupling of cell–cell junctions to the cytoskeleton and highlight the central role of α-catenin in this linkage. We assemble current knowledge about α-catenin’s regulation by tension and about its interactions with a diversity of proteins. We present a model in which α-catenin is a force-regulated platform for a machinery of proteins that orchestrates local cortical remodeling in response to force. Finally, we highlight recently described fundamental processes in tissue morphogenesis and argue where and how this α-catenin-dependent cadherin mechanotransduction may be involved. 相似文献