Cytoplasmic proteins, association with phospholipid vesicles and its dependency on cholesterol.

Okimasu, Eiji; Fujii, Yoshitaka; Utsumi, Toshihiko; Yamamoto, Masazumi; Utsumi, Kozo

doi:10.1247/csf.11.273

Cited by 3 publications

(1 citation statement)

References 29 publications

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“…The possibility that actin may also interact directly with membrane lipids has rarely been envisaged, having been mentioned in only a few preliminary reports. Okimasu et al (1986) showed that liposomes are able to bind many cytoplasmic proteins, and they identified one of these as F-actin.…”

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confidence: 99%

Actin conformation is drastically altered by direct interaction with membrane lipids: A differential scanning calorimetry study

Gicquaud

1993

Biochemistry

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One of the current dogmas in cytoskeleton research holds that actin filaments are attached to the cell membrane through integral membrane actin-binding proteins. We have challenged this concept, using an in vitro system composed of pure actin and liposomes, and have found that actin may also interact with membrane lipids. Differential scanning calorimetry (DSC) shows that when the actin molecule is in contact with such lipids, it undergoes a major conformational change which results in the complete disappearance of its phase transition. Conversely, DSC scans reveal that the phase transition of the membrane lipids is only weakly affected by the presence of actin. Indeed, the lipids' main transition shows only slight shifts in Tm, from 56.6 to 57 degrees C, and delta Hcal, from 10.1 to 8.8 kcal/mol. In the lipids' pretransition, Tp is shifted from 52.7 to 53.7 degrees C, and delta Hcal is shifted from 0.75 to 0.33 kcal/mol. This interaction between purified actin and membrane lipids is inhibited by high concentrations of KCl, thus indicating that the phenomenon is primarily electrostatic in nature. The ultrastructural consequences of this change in actin conformation were investigated by electron microscopy, which revealed the formation of paracrystalline arrays of actin filaments at the surface of the liposomes. We therefore propose a model in which a limited number of lipid molecules may interact with specific sites on the actin molecule, resulting in the protein's observed conformational change.

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mentioning

confidence: 99%

Actin conformation is drastically altered by direct interaction with membrane lipids: A differential scanning calorimetry study

Gicquaud

1993

Biochemistry

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Annexin I and its Biochemical Properties

Sato¹,

Tanaka²,

Edashige³

et al. 1991

Novel Calcium-Binding Proteins

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Inhibitory effect of cholesterol on interaction between cytoplasmic actin and liposomes, and restorative effect of high osmotic pressure.

Okimasu

Nobori

Kobayashi

et al. 1987

Cell Struct. Funct.

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Although cholesterol is one of the major components of plasma membranes in eukaryotic cells, very little is known about its role in biological membranes. We reported previously (Okimasu et al., Cell Struct. Funct. 11, 273-283, 1986) that introduction of cholesterol into the liposomal membrane caused a decrease in membrane permeability, especially by the binding of cytoplasmic proteins to the liposomal membrane. The present study was carried out to further clarify the biochemical function of cholesterol in the membrane-protein interactions, especially under high osmotic pressure. The association of membranes with cytoplasmic proteins and their permeability were decreased by the introduction of cholesterol, but its effects were diminished in a hypertonic medium. The protein species associated with cholesterol-containing liposomes vary depending on the sort of hypertonic condition. It was suggested that since the degree of lipid packing by the cholesterol was reduced by the locally increased curvature in the lipid bilayer under high osmotic pressure, some cytoplasmic proteins can penetrate into the liposomal membrane.

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Cytoplasmic proteins, association with phospholipid vesicles and its dependency on cholesterol.

Cited by 3 publications

References 29 publications

Actin conformation is drastically altered by direct interaction with membrane lipids: A differential scanning calorimetry study

Actin conformation is drastically altered by direct interaction with membrane lipids: A differential scanning calorimetry study

Annexin I and its Biochemical Properties

Inhibitory effect of cholesterol on interaction between cytoplasmic actin and liposomes, and restorative effect of high osmotic pressure.

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