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Biomedical subjects

D S Papermaster

Publications and source records attributed to D S Papermaster.

64 records · Page 4Linked to original sources
PubMed1975

Membrane protein analysis by two-dimensional immunoelectrophoresis.

Water-soluble membrane proteins may be analyzed by a new, rapid technique that combines electrophoresis on high-resolution sodium dodecyl sulfate (SDS) polyacrylamide gels and immunoelectrophoresis. After separation in the first dimension by electrophoresis in SDS, the proteins are subjected to a second electrophoresis at right angles through a two-layered buffered agarose gel. They first pass through a layer containing Lubrol PX which forms complexes with free SDS and then into an antiserum layer where antigen-antibody precipitates form. Precipitin arcs appear at positions corresponding to the antigens separated in the first dimension. The effectiveness of the technique was demonstrated with frog and cattle opsins, human erythrocyte membrane proteins, and their rabbit antiserums and for several water soluble proteins. By this method two fundamental parameters, molecular weight and antigenicity, may be readily used for analysis of membrane proteins.

Cell Membrane↗
PubMed1975

Membrane biosynthesis in the frog retina: opsin transport in the photoreceptor cell.

Rhodopsin biosynthesis and transport in the photoreceptor cell have been analyzed by subcellular fractionation of frog retinas after short periods of radioactive amino acid incorporation in vivo. Labelled membrane proteins were identified by autoradiography or sodium dodecyl sulfate-polyacrylamide gels. One of the most intensly labeled proteins in retina had a molecular weight comparable to opsin isolated from purified rod outer segments (ROS). Incorporation of label into this protein was rapid; the relative specific activity then diminished after the first 2 hr as radioactivity was transferred from retinal subcellular fractions to ROS. The kinetics of this transfer resembled rates previously observed by Hall et al. (Hall, M. O., Bok, D., and Bacharach, A.C.E. (1969), J. Mol. Biol. 45, 397). To identify the rapidly labeled protein as opsin we devised a new technique of two-dimensional immunoelectrophoresis of detergent solubilized membrane proteins. Antibodies were prepared against both whole ROS and opsin. After initial separation of retinal proteins on sodium dodecyl sulfate-polyacrylamide gels, a second dimension of electrophoresis in agarose, containing antisera, resulted in the formation of specific immunoprecipitates. Immunochemical analysis of all membranous and soluble retinal subcellular fractions indicated that newly synthesized opsin was membrane bound upon completion of synthesis. At no period of incorporation was a soluble form of newly synthesized opsin detectable. On this basis, we suggest that this protein is apparently transported as a water-insoluble membrane-bound molecule through the cytoplasm or along membranes of the inner segment to its assembly site near the base of the outer segment.

Amino Acids↗
PubMed1975

A new form of hereditary retinal degeneration in Wag/Rij rats.

A spontaneous, hereditable, bilateral retinal degeneration affecting all adult animals in a closed, imbred colony of Wag/Rij rats has been discovered. The disorder is characterized by early onset and a slow progressive course. Early lesions are detected by one month in retinas which are otherwise fully developed. Destruction of the photoreceptor layer proceeds as more and more cells degenerate. Degeneration appears to begin in the photoreceptor cell body and only secondarily affects the outer segment. Futhermore, phagocytic activity of pigment epithelium remains intact until late in the disease. Endstage lesions include retinal disorganization, proliferation and vascularization of pigment epithelium, and migration of pigment epithilial cells into the retina. The temporal and structural characteristics of this retinopathy indicate it may serve as a useful model for study of retinitis pigmentosa in man.

Age Factors↗
PubMed1970

Isolation of the fundamental polypeptide subunits of biological membranes.

A group of peptides (some or all of them glycopeptides), of molecular weight about 5000, has been shown to be a major fraction of biological membranes. These "miniproteins" have been prepared from membranes of human and bovine red blood cells, from purified bovine liver mitochondria, and from the rhodopsin-containing membranes of the outer segments of bovine retinal rods. While the miniproteins were found in large amounts in each case, the other protein components differed markedly depending on the function of the membrane studied. This fact was particularly clear in the case of the rod membranes where the only major proteins detected were the miniproteins and rhodopsin. The large size of the miniprotein fraction in each of these membranes leads us to propose that the miniproteins play a fundamental role in the several functions which occur as common denominators in biological membranes.

Animals↗