Search PubMed⌕ Search

Biomedical subjects

M Tokunaga

Publications and source records attributed to M Tokunaga.

At least 271 records · Page 15Linked to original sources
PubMed1982

Prolipoprotein signal peptidase in Escherichia coli is distinct from the M13 procoat protein signal peptidase.

We have previously reported a signal peptidase activity in Escherichia coli cell envelope which processes prolipoprotein modified with glyceride (Tokunaga, M., Tokunaga, H., and Wu, H. C. (1982) Proc. Natl. Acad. Sci. U. S. A. 79, 2255-2259). To ascertain whether the processing enzyme for prolipoprotein is distinct from the signal peptidase for M13 procoat protein purified by Zwizinski and Wickner (Zwizinski, C., and Wickner, W. (1980) J. Biol. Chem. 255, 7973-7977), we have used antibody against purified procoat protein signal peptidase to study the processings of prolipoprotein and M13 procoat protein in vitro. the signal peptidase for modified prolipoprotein remained fully active in solubilized membrane preparations which had been treated with antibody against purified procoat protein signal peptidase whereas the activity towards procoat protein was completely abolished by immunoadsorption. Furthermore, both unmodified and glyceride-modified prolipoprotein were not cleaved by the highly purified signal peptidase preparation provided by Wickner. These data clearly indicate that prolipoprotein signal peptidase is distinct from the M13 procoat protein signal peptidase.

Antigen-Antibody Complex↗
PubMed1982

Post-translational modification and processing of Escherichia coli prolipoprotein in vitro.

Escherichia coli strain MM18 cells containing malE-lacZ hybrid protein was reported to accumulate prolipoprotein when they were induced with maltose [Ito, K., Bassford, P. J. & Beckwith, J. (1981) Cell 24, 707-717]. We have shown that the prolipoprotein accumulated in maltose-induced MM18 cells is not modified, lacking covalently linked glyceride. When the cell envelope of MM18 containing unmodified prolipoprotein was incubated in the presence of detergent with [2-3H]glycerol-labeled cell envelope of strain JE5505 lacking murein lipoprotein, incorporation of [2-3H]glycerol radioactivity into both prolipoprotein and processed mature lipoprotein was observed. Likewise, when [3H]-palmitate-labeled JE5505 cell envelope was incubated with the MM18 cell envelope containing unmodified prolipoprotein in the presence of detergent, [3H]palmitate radioactivity was incorporated into prolipoprotein by ester linkage and into mature lipoprotein by both ester and amide linkages. These results indicate that our in vitro system contains activities of prolipoprotein modification and processing enzymes, including glyceryltransferase, O-acyltransferase, signal peptidase, and N-acyltransferase. The signal peptidase activity in our in vitro system was completely inhibited by globomycin. At pH 5.0, glyceryltransferase was inactive. Signal peptidase was active at pH 5.0, provided that prolipoprotein had been modified by glyceryltransferase (O-acyl-transferase) during a prior incubation at pH 9.1. These results strongly suggest that the modification of prolipoprotein by glyceryltransferase (and O-acyltransferase) precedes, and may in fact be a prerequisite for, the processing of prolipoprotein by signal peptidase.

Bacterial Proteins↗
PubMed1982

Image analysis of electron micrographs of ATPase (Coupling Factor TF1) from thermophilic bacteria and luminal epithelium of mouse urinary bladder.

Electron micrographs of two dimensional array of H+-ATPase (Coupling Factor TF1 from the thermophilic bacteria) and luminal epithelial protein of urinary bladder were obtained using negative staining method and freeze-fracture method, respectively. Images which showed good optical diffraction pattern were digitized by a computer-linked flat-bed two dimensional microdensitometer and processed digitally. The results of translational computer noise filtering showed that the outline of TF1 molecules looks like a hexagon or an asterisk in the presence of sodium azide which is a specific inhibitor of TF1 or AMPPNP which is an unsplitable analogue of ATP, respectively. The luminal epithelial protein also looks like a hexagon. Rotational harmonic analysis was carried out to examine the rotational symmetry of the filtered images of TF1. It was found that 2-fold or 6-fold symmetry is dominant in the presence of sodium azide or AMPPNP, respectively.

Adenosine Triphosphatases↗
PubMed1982

Ultrastructure of adult T-cell lymphoma.

A particular type of adult T-cell lymphoma which occasionally progress to leukemia has been widely accepted as endemic in a restricted area of Kyushu Island in the southwest part of Japan. This type of non-Hodgkin's lymphoma is called peripheral T-cell lymphoma, pleomorphic lymphoma or adult T-cell leukemia. In this report, the cellular characteristics of 34 cases of adult T-cell lymphoma-leukemia were analyzed by electron microscopy. The most prominent feature of adult T-cell lymphoma is nuclear pleomorphism, primarily characterized by nuclear convolution, multilobulation and fragmentation.

Cell Nucleus↗
PubMed1981

Permeability properties of chemically modified porin trimers from Escherichia coli B.

The pore-forming protein of the outer membrane of Escherichia coli, porin, was chemically modified with acetic anhydride, succinic anhydride, and glycinamide. Extensive modification of amino groups of the functional porin trimers caused reduced diffusion rates of the negatively charged solutes such as p-nitrophenyl phosphate and AMP, but did not reduce significantly the diffusion of positively charged molecules carbobenzoxy-glycyl-prolyl-arginine-p-nitranilide and tosyl-glycyl-prolyl-arginine-p-nitranilide. Modification of carboxyl groups of trimers caused decreased diffusion rates of the positively charged solutes more significantly than the diffusion rates of negatively charged solutes. The results suggest that the ionic interactions play an important role for the diffusion of charged solutes through the porin pore. The diffusion of p-nitrophenyl alpha-D-glucoside, an uncharged solute, ws not influenced significantly by modification of either amino or carboxyl groups. This observation suggests that modifications only occurred in areas outside of the narrowest portion of the pore or, alternatively, that amino and carboxyl groups are exclusively located at noncylindrical area of the pore. The structural integrity of the acetylated and the succinylated trimers seemed well preserved. On the other hand, modification of carboxyl groups decreased the thermal stability of trimers and extensive modifications caused the dissociation of trimers into monomers at 37 degrees C.

Acetic Anhydrides↗
PubMed1981

Change of prostaglandin E level in joint fluids after treatment with flurbiprofen in patients with rheumatoid arthritis and osteoarthritis.

The prostaglandin E (PGE) level in the knee joint fluid was determined by radioimmunoassay before and after anti-inflammatory therapy with flurbiprofen in 8 patients with rheumatoid arthritis (RA) and 4 patients with osteoarthritis (OA). The level of PGE in RA joint fluids before the anti-inflammatory treatment was 9.5-1.2 ng/ml and in proportion with the leucocyte count in the joint fluid. A marked decrease of the PGE level was attained with flurbiprofen treatment in 4 patients whose initial PGE levels had been higher than 3.2 ng/ml, while 4 patients with lower PGE levels, namely, 1.4-1.2 ng/ml, did not respond to the drug treatment. In all the OA patients the PGE levels was no higher than 1.5 ng/ml and refractory to the anti-inflammatory therapy.

Adult↗
PubMed1981

Lipid composition of adipose tissue from "membranous lipodystrophy".

The lipid composition of the adipose tissue from the bone marrow and that of the subcutaneous depot fat of four patients of membranous lipodystrophy were investigated. It was found that the lipid composition of the samples from the cases of membranous lipodystrophy was almost similar to that in controls. Also discussions were made on mechanism related to the accumulation of abnormal depot fat.

Adipose Tissue↗
PubMed1980

Non-Hodgkin's lymphomas in a southern prefecture in Japan: an analysis in 715 cases.

As of March 1978, the prognosis was confirmed in 715 non-Hodgkin's lymphoma cases reported during the 12-year period from 1965 through 1976 in the Prefecture of Kagoshima. Included were 222 cases of extranodal lymphoma. Patients with the initial tumor site in the gastrointestinal tract and Waldeyer's ring had a relatively good probability of survival. Among the patients with cutaneous lymphomas, those with the mycosis fungoides type had a poor survival rate. In Kagoshima Prefecture, the survival curve for cases of nodal lymphomas is characteristically much poorer than those reported in the medical literature. Of the nodal lymphomas, the nodular type was found in 128 cases and the five-year survival rate was 15%, while the diffuse type accounted for 365 cases and the five-year survival rate was 8%. The paracortex type, considered to be of T-cell origin, accounted for 55 cases and the five-year survival rate was 0%. These differences were statistically significant. Based on our data, the classification of nodular lymphomas into subtypes according to the degree of nodularity was found to be useful since it was related to clinical stage and survival. Rappaport's cellular classification of diffuse lymphoma is related to prognosis and was found to be useful, but problems still remain in determining T- and B-cell types by means of cellular morphology and thus further study is warranted.

Female↗