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1

Effect of divalent metal ions on annexin-mediated aggregation of asolectin liposomes.

100%

Vladimir I Mel'gunov , Akimova E. I. , Krasavchenko K. S.

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nr 3

675-683

EN

Annexins belong to a family of Ca2+- and phospholipid-binding proteins that can mediate the aggregation of granules and vesicles in the presence of Ca2+. We have studied the effects of different divalent metal ions on annexin-mediated aggregation of liposomes using annexins isolated from rabbit liver and large unilamellar vesicles prepared from soybean asolectin II-S. In the course of these studies, we have found that annexin-mediated aggregation of liposomes can be driven by various earth and transition metal ions other than Ca2+. The ability of metal ions to induce annexin-mediated aggregation decreases in the order: Cd2+>Ba2+, Sr2+>Ca2+>>Mn2+>Ni2+>>Co2+. Annexin-mediated aggregation of vesicles is more selective to metal ions than the binding of annexins to membranes. We speculate that not every type of divalent metal ion can induce conformational change sufficient to promote the interaction of annexins either with two opposing membranes or with opposing protein molecules. Relative concentration ratios of metal ions in the intimate environment may be crucial for the functioning of annexins within specialized tissues and after treatment with toxic metal ions.

2

Annexins-multifunctional, calcium-dependent, phospholipid-binding proteins

100%

Bandorowicz J. , Pikula S.

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nr 3

3

The roles of annexins and alkaline phosphatase in mineralization process.

88%

Balcerzak M. , Hamade E. , Zhang L. , Pikula S. , Azzar G. , Radisson J. , Bandorowicz-Pikula J. , Buchet R.

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nr 4

1019-1038

EN

In this review the roles of specific proteins during the first step of mineralization and nucleation are discussed. Mineralization is initiated inside the extracellular organelles-matrix vesicles (MVs). MVs, containing relatively high concentrations of Ca2+ and inorganic phosphate (Pgi), create an optimal environment to induce the formation of hydroxyapatite (HA). Special attention is given to two families of proteins present in MVs, annexins (AnxAs) and tissue-nonspecific alkaline phosphatases (TNAPs). Both families participate in the formation of HA crystals. AnxAs are Ca2+- and lipid-binding proteins, which are involved in Ca2+ homeostasis in bone cells and in extracellular MVs. AnxAs form calcium ion channels within the membrane of MVs. Although the mechanisms of ion channel formation by AnxAs are not well understood, evidence is provided that acidic pH or GTP contribute to this process. Furthermore, low molecular mass ligands, as vitamin A derivatives, can modulate the activity of MVs by interacting with AnxAs and affecting their expression. AnxAs and other anionic proteins are also involved in the crystal nucleation. The second family of proteins, TNAPs, is associated with Pi homeostasis, and can hydrolyse a variety of phosphate compounds. ATP is released in the extracellular matrix, where it can be hydrolyzed by TNAPs, ATP hydrolases and nucleoside triphosphate (NTP) pyrophosphohydrolases. However, TNAP is probably not responsible for ATP-dependent Ca2+/phosphate complex formation. It can hydrolyse pyrophosphate (PPi), a known inhibitor of HA formation and a byproduct of NTP pyrophosphohydrolases. In this respect, antagonistic activities of TNAPs and NTP pyrophosphohydrolases can regulate the mineralization process.

4

Interactions of annexins IV and VI with erythrocyte membrane in the presence of Ca2. A biochemical and electron microscopy study

63%

Bandorowicz-Pikula J. , Sobota A.

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nr 1

EN

Annexins IV and VI were found to interact with human erythrocyte membrane in a calcium-dependent manner. Chemical and enzymatic modification of the membrane constituents pointed to phosphatidylserine as a target membrane molecule responsible for the interaction of the annexin/Ca complexes with the membrane. The membrane-associated annexins were shown to form clusters reflecting, perhaps, the presence of PS microdomains in a lateral plane of membrane.

5

Calcium signaling in the brain

51%

Heizmann C. W.

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tom 53

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nr 1

6

Bile flow, vesicular trafficking, and interactions of cytoskeleton with the canalicular domain of hepatocyte plasma membrane

51%

Pikula S. , Bandorowicz-Pikula J.

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nr 2

EN

Liver is an epithelial organ which removes many substances from the blood, metabolizes them, and secretes back into circulation or directly into the bile. Liver parenchymal cells (hepatocytes) are involved in the overall detoxification of the organism through the bile. These highly polarized cells are unique among others due to the domain structure of their plasma membrane, organization of their cytoskeleton connected to the canalicular region of plasmalemma, and the specific distribution of various transport systems involved in detoxification phase III. In this mini-review the possible influence of canalicular motility modulated by cytoskeleton on the bile flow is discussed. In addition, the role of annexins, calcium- and phospholipid-binding proteins exhibiting high expression level in liver, in vesicular trafficking leading to the transport of some of biliary components is also postulated.