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Biomedical subjects

W J Rutter

Publications and source records attributed to W J Rutter.

At least 253 records · Page 14Linked to original sources
PubMed1973

Early differentiation of glucagon-producing cells in embryonic pancreas: a possible developmental role for glucagon.

Glucagon and insulin are first detectable at the onset of rat pancreas organogenesis. Initially, the specific activity of glucagon is approximately 100-fold higher than that of insulin. At this early stage, endocrine storage granules, similar to alpha granules, are identifiable in electron micrographs. The granule characteristics, as well as the relative hormone levels, suggest that the early population of differentiated endocrine cells is in fact composed of glucagon-producing (A) cells. This high level of glucagon is present in the embryo much earlier than the metabolic processes thought to be controlled by this hormone. Moreover, glucagon-producing cells may be the first endocrine cells to differentiate. Other known endocrine products accumulate later, during the terminal stages of organogenesis. These observations suggest that glucagon may have a regulatory function in early embryogenesis.

Animals↗
PubMed1971

Molecular structures of DNA-dependent RNA polymerases (II) from calf thymus and rat liver.

DNA-dependent RNA polymerase II has been purified to high specific activity and apparent homogeneity from both calf thymus and rat liver. Two form II enzymes are present in rat-liver preparations, one with the molecular structure [(190,000)(1)(150,000)(1)(35,000)(1)(25,000)(1)], the other with a molecular structure of [(170,000)(1)(150,000)(1)(35,000)(1)(25,000)(1)] (molecular weights are within +/-5% but the absolute values are approximate). Inclusion of a proteolytic inhibitor during the isolation procedure decreases the proportion of the molecule containing the 170,000 subunit. Calf-thymus RNA polymerase preparations typically exhibit four components on polyacrylamide gels that contain sodium dodecyl sulfate, with an apparent molecular structure of [(190,000)(1)(150,000)(1)(35,000)(1)(25,000)(1)]. In addition, some calf-thymus polymerase II preparations contain small quantities of the [(170,000)(1)(150,000)(1)(35,000)(1)(25,000)(1)] species; the quantity of this species may also be increased from less than 5% in the normal preparation to at least 40% in an "aged" preparation. Thus, the 170,000 subunit may be derived from the 190,000 subunit in both tissues. Until unequivocal evidence is obtained on this point, however, the possibility that the large subunits are unique species should not be eliminated. The general structural similarity of the eukaryotic RNA polymerase II with that of the prokaryotic polymerase suggests that the modes of action and regulation may be analogous.

Acrylamides↗