Gary R. Craven

Bio: Gary R. Craven is an academic researcher from National Institutes of Health. The author has contributed to research in topics: Ribosomal protein & 30S. The author has an hindex of 6, co-authored 12 publications receiving 727 citations.

Three-dimensional organization of the 30S ribosomal proteins from Escherichia coli. I. Preliminary classification of the proteins.

Abstract: 30S ribosomal subunits from Escherichia coli were reacted with three protein reagents. After reaction, the ribosomal proteins were extracted and examined; of the 20 proteins known to compose the particle, nine did not react with any of the three reagents. We have tentatively classified these proteins as „internal,” and the remaining eleven as „external.” A strong correlation was found between these results and the sequence of assembly. Those proteins which enter the assembly process early are classed as internal, whereas those proteins found to participate later in the assembly sequence are classed as external.

Gene structure and extracellular secretion of Neisseria gonorrhoeae IgA protease

Abstract: Several human bacterial pathogens, including the Gram-negative diplococcus Neisseria gonorrhoeae, produce extracellular proteases that are specific for human immunoglobulin IgA1, (refs 1, 2). Immunoglobulin A (IgA) proteases have been studied extensively and the genes of some species cloned in Escherichia coli3–7, but their role in pathogenesis remains unclear8. Recently we derived a DNA fragment of 5 kilobases (kb) from N. gonorrhoeae MS 11 directing extracellular active enzyme in E. coli4. Although the mature enzyme of strain MS 11 was shown to have a relative molecular mass of 106,000 (Mr 106K) in gels4, the DNA sequence of this cloned fragment reveals a single gene coding for a 169K precursor of IgA protease. The precursor contains three functional domains, the amino-terminal leader which is assumed to initiate the inner membrane transport of the precursor, the protease, and a carboxyl-terminal 'helper' domain apparently required for extracellular secretion (excretion). Based on the structural features of the precursor, we propose a model in which the helper serves as a pore for excretion of the protease domain through the outer membrane. IgA protease acquires an active conformation as its extracellular transport proceeds and is released as a proform from the membrane-bound helper by autoproteolysis. The soluble proform further matures into the 106 K IgA protease and a small stable α-protein.

Enzyme-labeling of antibodies and their fragments for enzyme immunoassay and immunohistochemical staining.

Abstract: The use of an enzyme as a label has a number of advantages over the use of other labels in both immunohistochemistry and immunoassay. Immunofluorescence techniques are not suitable for ultrastructural research on cells, and ferritin-labeled antibodies allow only electronmicroscopic studies. By contrast, enzyme-labeled antibodies permit localization of cellular antigens in relation to tissue structures under light microscope and also demonstration of cellular antigens at an ultrastructural level by electronmicroscopy. Antibody or antibody fragments labeled with enzymes of small molecular weight can more readily permeate cells of tissue sections than ferritin-labeled antibodies. The color of tissue sections prepared by immunoenzymatic techniques is stable for years, while immunofluorescence of tissue sections decreases rapidly when exposed to light. Radioisotope-labeled reagents decay with time; there are health hazards due to radio isotopes; and disposal of radioactive waste is becoming increasing...