Generalized Membrane Defect Research Articles

Electron spin resonance investigations of membrane proteins in erythrocytes in muscle diseases. Duchenne and myotonic muscular dystrophy and congenital myotonia

Comparison of electron spin resonance spectra of spin labeled erythrocyte membranes from patients with the dystrophic conditions Duchenne and myotonic muscular dystrophy with those of normal controls suggests that alterations in membrane protein conformation and/or organization are present in these disease states. These protein alterations are not apparent in the nondystrophic disease congenital myotonia. The results suggest a correlation between changes in the physical state of protein in membranes with the presence of dystrophy. In addition, the present results from erythrocytes lend support for the concept of a generalized membrane defect in these diseases.

Erythrocyte membrane abnormality in muscular dystrophy

We found that erythrocyte membranes of dystrophic mice were considerably altered as measured by the technique of whole cell aqueous polymer partitioning. The difference was directly linked to the sex of the animal. Littermates of the diseased animals (genetic carriers or 'expressers') also had erythrocytes that were dramatically different from the sexand age-matched normals. The data show conclusively absolute differences in erythrocyte membranes from dystrophic animals. This observation has two implications: 1) expression of muscular dystrophy is not confined to muscle, and 2) the disease may be a general membrane defect instead of an abnormality of other cellular organelles. The prime defect in the group of diseases classified as muscular dystrophies is unknown except descriptively from the disease name--l.e., dystrophy of muscles (1,2). Furthermore, no curative therapy is known. Many investigators have been interested in whether the disease is manifest in organs other than muscle, and the idea of a systemic membrane defect has been advanced (3,4). Using aqueous polymer partitioning we are able to show definite alterations in erythrocyte membranes in dystrophic mice. Aqueous polymer partitioning is a sensitive technique for measuring properties of surface membranes (5,6). The technique is so sensitive that it is possible to identify subtle differences between membranes. However, the significance of these differences in partitioning ratios is uncertain-it can be shown only that a difference exists--but best speculations are that the technique

Apparent alterations of erythrocyte acetylcholinesterase and other membrane proteins in Duchenne muscular dystrophy: a further example of a generalized membrane defect associated with hereditary muscular dystrophy.

Apparent alterations of erythrocyte acetylcholinesterase and other membrane proteins in Duchenne muscular dystrophy: a further example of a generalized membrane defect associated with hereditary muscular dystrophy.

Multiple alterations in metabolite uptake in a mutant of Neurospora crassa.

A temperature-conditional lethal mutant of Neurospora crassa, un-t (55701), was resistant to neutral amino acid analogues by virtue of a decreased ability to transport these analogues and their natural congeners across the cell membrane. The uptake of acidic, but not basic, amino acids was also impaired, as was the uptake of potassium ions. After preincubation above the tolerated temperature, the ability to take up a still wider variety of metabolites was greatly reduced. Protoplasts of the mutant were more osmotically fragile than those of wild type. The possibility that the mutant has a generalized membrane defect is discussed.