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Biomedical subjects

E F Luscher

Publications and source records attributed to E F Luscher.

7 recordsLinked to original sources
PubMed1986

Glycoprotein Ib beta is the only phosphorylated major membrane glycoprotein in human platelets.

Platelets were metabolically labelled with 32P and the phosphoproteins examined by two-dimensional non-reduced/reduced gel electrophoresis and isoelectric-focusing/gel electrophoresis. Comparison with similar separations of surface-labelled platelets showed that the only major glycoprotein which is phosphorylated is the beta-subunit of glycoprotein Ib, indicating that this subunit contains a cytoplasmic segment. The identification was confirmed using immunoblotting with an antibody to the beta-subunit. Phosphoserine was the principal phosphorylation site, with some phosphothreonine, but phosphotyrosine was absent. No quantitative or qualitative differences could be detected in the phosphorylation of glycoprotein Ib beta from resting or activated platelets. These results exclude changes in phosphorylation of the major platelet membrane glycoproteins as a method of signal transmission by these receptors.

Binding Sites↗
PubMed1980

Characterization of human blood platelet membrane proteins and glycorproteins by their isoelectric point (pI) and apparent molecular weight using two-dimensional electrophoresis and surface-labelling techniques.

Intact human blood platelets were radioactively labelled at the surface by techniques specific for proteins or glycoproteins. Labelled platelet samples were analyzed by a high-resolution two-demensional separation system involving isoelectric focusing in the first dimension and discontinuous sodium dodecyl sulphate-polyacrylamide gel electrophoresis in the second. The major platelet membrane glycoprotein (GP) bands (Ib, IIb, IIIa and IIIb) were found to be highly heterogeneous even after removal of terminal sialic acid residues. Lactoperoxidase-catalyzed iodination of platelets showed that the major labelled proteins (Ib, IIb, IIIa and IIIb) had altered isoelectric points (pI) and molecular weights after neuraminidase treatment. A number of membrane glycoproteins previously undetected by one-dimensional gel electrophoresis were demonstrated and good evidence provided that the major platelet surface proteins are glycosylated.

Blood Platelets↗
PubMed1977

Isolation of the membrane glycoproteins of human blood platelets by lectin affinity chromatography.

The major platelet membrane glycoproteins have been solubilized in 1.0% sodium deoxycholate and subjected to affinity chromatography on the lectins from Lens culinaris, wheat germ and Abrus precatorius. Polyacrylamide gel electrophoresis in the presence and absence of a reducing agent together with the differential binding of the lectins to the glycoproteins permitted the distinction of at least seven separate glycoprotein entities. A new nomenclature for the glycoproteins is proposed to accomodate the additional data. Using combinations of lectin columns, glycoproteins Ia and Ib could be prepared in a pure state and IIb and IIIa could be greatly purified. The binding of lectins to glycoprotein Ib has been strongly implicated as a necessary step in the aggregation response of platelets to lectins.

Blood Platelets↗
PubMed1975

Actin in the cytoplasm of adrenocortical cells.

Rat or hamster adrenocortical cells contain a network of filaments mostly 40-80 A in diameter, which is particularly evident at the cell periphery. In frozen sections, adrenocortical cells fix (particularly at their periphery) anti-actin autoantibodies present in sera of patients with chronic aggressive hepatitis. It is concluded that the peripheral network of adrenocortical cells contains contractile proteins (at least actin) and the implication of such proteins in steroid secretion is discussed.

Actins↗