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Intracellular Functions (intracellular + function)

Distribution by Scientific Domains

Life Sciences	40%

Selected Abstracts

Intracellular function in rehydrated lyophilized platelets

BRITISH JOURNAL OF HAEMATOLOGY, Issue 1 2000
Thomas H. Fischer
This study aimed to evaluate the effect of cross-linking and lyophilization on intracellular signalling processes in rehydrated, lyophilized (RL) platelets, which are under development as a platelet substitute for transfusion. Exposure of RL platelets to thrombin resulted in enhanced phosphorylation of several proteins, including 18 kDa and 42 kDa kinase substrates that were shown to be the substrates of myosin light chain and protein kinase C respectively. Cross-linking and lyophilization depleted the platelets of free cytoplasmic ADP and ATP, but had less effect on protein-bound nucleotides. The surface membrane of RL platelets was found to be permeable to poly dT probes less than approximately 3 kDa in size; larger nucleotide probes and proteins did not penetrate the surface membrane. Taken together, our results indicate that RL platelets retain some of the haemostatic stimulus-response functions of fresh platelets and are capable of feedback amplification in coagulation. [source]

Modulation of inositol 1,4,5-triphosphate concentration by prolyl endopeptidase inhibition

FEBS JOURNAL, Issue 23 2002
Ingo Schulz
Prolyl endopeptidase (PEP) is a proline-specific oligopeptidase with a reported effect on learning and memory in different rat model systems. Using the astroglioma cell line U343, PEP expression was reduced by an antisense technique. Measuring different second-messenger concentrations revealed an inverse correlation between inositol 1,4,5-triphosphate [Ins(1,4,5)P3] concentration and PEP expression in the generated antisense cell lines. However, no effect on cAMP generation was observed. In addition, complete suppression of PEP activity by the specific inhibitor, Fmoc-Ala-Pyrr-CN (5 µm) induced in U343 and other cell lines an enhanced, but delayed, increase in Ins(1,4,5)P3 concentration. This indicates that the proteolytic activity of PEP is responsible for the observed effect. Furthermore, the reduced PEP activity was found to amplify Substance P-mediated stimulation of Ins(1,4,5)P3. The effect of reduced PEP activity on second-messenger concentration indicates a novel intracellular function of this peptidase, which may have an impact on the reported cognitive enhancements due to PEP inhibition. [source]

Dissecting the signal transduction pathways triggered by galectin,glycan interactions in physiological and pathological settings

IUBMB LIFE, Issue 1 2010
Diego J. Laderach
Abstract Galectins are a family of evolutionarily conserved animal lectins with pleiotropic functions and widespread distribution. Fifteen members have been identified in a wide variety of cells and tissues. Through recognition of cell surface glycoproteins and glycolipids, these endogenous lectins can trigger a cascade of intracellular signaling pathways capable of modulating cell differentiation, proliferation, survival, and migration. These cellular events are critical in a variety of biological processes including embryogenesis, angiogenesis, neurogenesis, and immunity and are substantially altered during tumorigenesis, neurodegeneration, and inflammation. In addition, galectins can modulate intracellular functions and this effect involves direct interactions with distinct signaling pathways. In this review, we discuss current knowledge on the intracellular signaling pathways triggered by this multifunctional family of ,-galactoside-binding proteins in selected physiological and pathological settings. Understanding the "galectin signalosome" will be essential to delineate rational therapeutic strategies based on the specific control of galectin expression and function. © 2009 IUBMB IUBMB Life, 62(1):1,13, 2010 [source]

PRODUCTION OF PHYTOCHELATINS AND GLUTATHIONE BY MARINE PHYTOPLANKTON IN RESPONSE TO METAL STRESS,

JOURNAL OF PHYCOLOGY, Issue 5 2006
Silvia K. Kawakami
Phytoplankton deal with metal toxicity using a variety of biochemical strategies. One of the strategies involves glutathione (GSH) and phytochelatins (PCs), which are metal-binding thiol peptides produced by eukaryotes and these compounds have been related to several intracellular functions, including metal detoxification, homeostasis, metal resistance and protection against oxidative stress. This paper assesses our state of knowledge on the production of PCs and GSH by marine phytoplankton in laboratory and field conditions and the possible applications of PCs for environmental purposes. Good relationships have been observed between metal exposure and PC production in phytoplankton in the laboratory with Cd, Pb, and Zn showing the greatest efficacy, thereby indicating that PCs have a potential for application as a biomarker. Fewer studies on PC distributions in particulate material have been undertaken in the field. These studies show that free Cu has a strong relationship with the levels of PC in the particulate material. The reason for this could be because Cu is a common contaminant in coastal waters. However it could also be due to the lack of measurements of other metals and their speciation. GSH shows a more complex relationship to metal levels both in the laboratory and in the field. This is most likely due to its multifunctionality. However, there is evidence that phytoplankton act as an important source of dissolved GSH in marine waters, which may form part of the strong organic ligands that control metal speciation, and hence metal toxicity. [source]

Mechanical Characterization of Motor Proteins: A Molecular Dynamics Approach

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 7-8 2008
Iuliana Aprodu
Abstract A new approach, based on molecular dynamics, is presented to measure the mechanical properties of motor proteins, which are important for accomplishing their intracellular functions. Two different set-ups were designed to mimic the optical tweezers and surface force apparatus experiments. The results obtained show that the stiffness and elastic modulus of kinesin motor domain are 377 pN,·,nm,1 and 0.17 GPa, respectively, while the myosin motor domain is characterized by a stiffness of 271 pN,·,nm,1 and an elastic modulus of 0.26 GPa. These results suggest that the source of the very low stiffness detected for full-length molecules is located outside of the globular part of the proteins. [source]