Microviscosity parameters and protein mobility in biological membranes

Shinitzky, Meir; Inbar, Michael

doi:10.1016/0005-2736(76)90183-8

Cited by 671 publications

(214 citation statements)

References 52 publications

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“…These were obtained from measurement of fluorescence polarization on intact secretory vesieles [62]. These results were confirmed by applying the same method to liposomes composed of the total lipid extract of the same membranes [63].…”

Section: Fusion Of Liposomes Containing Various Con-centrations Of Cmentioning

confidence: 67%

Membrane fusion of secretory vesicles and liposomes Two different types of fusion

Ekerdt

Dahl²,

Gratzl³

1981

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Secretory vesieles isolated from adrenal medulla were found to fuse in vitro in response to incubation with Ca 2 +. Intervesicular fusion was detected by electron microscopy and was indicated by the appearance of twinned vesieies in freeze-fractured suspensions of vesieles and in thin-sectioned pellet. Two types of fusion could be distinguished: Type I, occurring between 10-7 M and 10-4 M Ca 2 +, was specific for ea 2 +, was inhibited by other divalent cations and was abolished by pretreatment of vesieles with glutaraldehyde, neuraminidase or trypsin. Fusion type I was linear with temperature. A second type of intervesicular fusion was elicited by Ca 2 + in concentrations higher than 2.5 mM and was morphologically characterized by multiple fusions of secretory vesicles. This type of fusion was found to be similar to fusion of liposomes prepared from the membrane lipids of adrenal medullary secretory vesieles: ea 2 + could be replaced by other divalent cations, the effect of different divalent cations was additive and pretreatments attacking membrane proteins were ineffective. Fusion type 11 of intact secretory vesieies as weil as liposome fusion was discontinuous with temperature. Liposome fusion could be detected within 35 ms and persisted for 180 min. Using liposomes containing defined Ca 2 + concentrations we have not found a major influence of Ca 2 + asymmetry on fusion. Incorporation of the ganglioside GM 3 , which is present in the membranes of intact adrenal medullary secretory vesicles did not change the properties of liposomes fusion. Using a Ca 2 +-selective electrode we have identified in secretory vesiele membranes both high affinity binding sites for Ca 2 + (/(} = 1.6 . 10-6 M) and low affinity sites (/(} = 1.2· 10-4 M).

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Section: Fusion Of Liposomes Containing Various Con-centrations Of Cmentioning

confidence: 67%

Membrane fusion of secretory vesicles and liposomes Two different types of fusion

Ekerdt

Dahl²,

Gratzl³

1981

Biochimica et Biophysica Acta (BBA) - Biomembranes

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“…Figure 6 illustrates the hypothetical use of a ratio of fluorescence of DiICe(5) (potential sensitive) and diphenylhexatriene (DPH) to improve resolution. The UV-excited blue fluorescence of DPH has been used as a probe of membrane microviscosity in cell suspensions by Inbar and Shinitzky (28,59) DiICs(5) exhibit essentially the same blue fluorescence as those treated with DPH alone, suggesting that there is little energy transfer from DPH to DiICs(5). In studies in which spatially separated UV and red laser beams were used for correlated measurements in CEM cells of DPH and DiICs(5) fluorescence and of the fluorescence ratio, there did not appear to be a strong cell-to-cell correlation of DPH and DiIC6(5) fluorescence.…”

Section: Resultsmentioning

confidence: 99%

Flow cytometric probes of early events in cell activation

Shapiro

1981

Cytometry

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By now, it's well established that the surface of a cell Contains transmembrane proteins which, on binding ligands, tell The biochemical computer inside what to do Without a need for any of the ligands coming through. Receptor‐triggered cytoplasmic “interrupt routines” May lead the nucleus to activate new sets of genes, Or otherwise induce a cell, which never reasons why, To twitch, secrete, endocytose, or reproduce, or die. By merely watching labeled ligands bind, we cannot know Down which of many paths the cells thus tagged are apt to go, But other changes, shortly after binding, may predict Which of its several options any given cell has picked. Flow cytometric methods are described here which allow Membrane potential to be estimated, to show how Potential changes may occur in seconds after binding Of ligand to a functional receptor, or for finding No change when cells don't have the right receptor, or can't see The ligand for antagonists of like affinity. With chlorotetracycline fluorescence, one can find Release of membrane calcium soon after ligands bind; Both this and the potential measurement can help support Decisions in an instrument about which cells to sort, Though narrowing the distributions which these methods yield Would greatly help to broaden applications in this field.

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“…The mechanism by which membrane rigidity favours capping of surface proteins remains to be established. An attractive possibility is the "squeezing out" of the membrane matrix of protein or protein-lipid complex, leading to a more peripheral position (Shinitzky and Inbar, 1976;Borochov and Shinitzky, 1976). However, the mechanism of capping is complex and it cannot be excluded that the observed correlation is an indirect rather than a direct one.…”

Section: Resultsmentioning

confidence: 99%

Membrane fluidity, capping of cell-surface antigens and immune response in mouse leukaemia cells

Hilgers¹,

Sluis²,

Blitterswijk³

et al. 1978

Br J Cancer

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Transplantation of primary GRSL cells in the ascitic form led to a decrease in membrane microviscosity as measured by the fluorescence polarization technique. The transplanted GRSL ascitic cells showed a markedly lower ability to form caps with respect to both virus-related (MLr, GIX) and normal (H-2.7(G), H-2.8(K) and TL1.2) cell-surface antigens and their appropriate antisera in the indirect membrane immunofluorescence tests, than did primary GRSL cells, transplanted GRSL cells growing in solid form, and thymocytes, which all exhibited significantly higher membrane microviscosities. Transplantation of primary GRSL cells into syngeneic mice pre-irradiated with 400 rad did not lead to a fall in membrane microviscosity. It is suggested that the host immune response in intact mice leads to a selective survival of ascitic tumour cells with low membrane microviscosity. Images Fig. 3

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Microviscosity parameters and protein mobility in biological membranes

Cited by 671 publications

References 52 publications

Membrane fusion of secretory vesicles and liposomes Two different types of fusion

Membrane fusion of secretory vesicles and liposomes Two different types of fusion

Flow cytometric probes of early events in cell activation

Membrane fluidity, capping of cell-surface antigens and immune response in mouse leukaemia cells

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