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T Funatsu

Publications and source records attributed to T Funatsu.

At least 73 records · Page 4Linked to original sources
PubMed1988

Transition of beta-actinin isoforms during development of chicken skeletal muscle.

We examined by means of the immunoblotting technique the transition of beta-actinin isoforms during the development of the chicken from 5 day embryo to adult. As an antigen, beta-actinin was prepared from adult chicken breast muscle (pectoralis major) and polyclonal antibody was obtained by injecting undenatured beta-actinin into a rabbit. Immunoblotting examination of breast muscle at several stages of development (except 5 day embryo, in which the whole body minus the head and limbs was examined) showed that the species of beta-actinin subunits change during development: 1) beta I is already present in 5 day embryo, whereas beta II appears only after 9 days. 2) In 5 day embryo, we found, instead of beta II, a new subunit (designated beta III) that cross-reacts with the antibody, has the apparent molecular weight of 30,000 daltons and has a slightly alkaline isoelectric point compared with beta I. The content of beta III gradually decreased and beta III completely disappeared a week after hatching. Such a type of transition of the isoforms in beta-actinin subunits is similar to that observed in other muscle proteins. The transition of beta-actinin isoforms may correlate to the organization of an I-Z-I brush, especially to the length determination of thin filaments, because the developmental stage at which beta III disappears coincides with that at which the length of thin filaments is strictly determined.

Actinin↗
PubMed1988

Beta-actinin isoforms in various types of muscle and non-muscle tissues.

We found that beta-actinin isoforms are present in various types of tissues in adult chicken by using immunoblotting after two dimensional gel electrophoresis; for this purpose, an antibody was raised against beta-actinin purified from adult chicken breast muscle (pectoralis major). One of the beta-actinin subunits, beta I, was present in all tissues we examined, i.e. skeletal (pectoralis major, semitendinosus, and anterior latissimus dorsi), cardiac, and smooth (gizzard) muscles, non-muscle (brain, liver, and kidney) tissues and blood, whereas another subunit, beta II, was present only in muscle tissues. A new subunit (designated beta III) that was found in the embryonic stages of skeletal muscle (Asami, Funatsu & Ishiwata (1988) J. Biochem. 103, 72-75) was present instead of beta II in non-muscle tissues and blood. In cardiac and smooth muscles, beta III coexisted with beta I and beta II. The antibody of beta-actinin did not cross-react to cytoplasmic beta-actinin (molecular weight, 80,000 daltons) found in kidney. It was suggested that the combination of beta I and beta III present in non-muscle tissues and blood is identical to the barbed end capping protein isolated from brain by Killiman and Isenberg (EMBO J. 1, 889-894 (1982)). It is likely that beta-actinin forms a genetic family whose constituents have an ability to cap either the pointed or barbed end of actin filaments.

Actinin↗
PubMed1987

Beta-actinin is not distinguishable from an actin barbed-end capping protein in chicken breast muscle.

beta-Actinin is an actin-pointed end capping protein in skeletal muscle. Casella et al. have reported that a protein isolated from muscle acetone powder by procedures similar to those used for beta-actinin purification caps the barbed end of an actin filament (J. Biol. Chem. 261, 10915-10921 (1986)). We have confirmed the above results. However, it turned out that the two proteins were identical as to subunit sizes, peptide maps, and cross-reactivities with anti-beta-actinin IgG. The binding of the two proteins to opposite ends of an actin filament remains unexplained.

Actin Depolymerizing Factors↗
PubMed1987

[Prosthetic reconstruction of the trachea and carina].

We have performed prosthetic reconstruction of the trachea and carina in 12 patients since 1979. We used Neville's prosthesis in 7 patients and Katsura's prosthesis in 5 patients. Seven patients were operated on for lung cancer, 2 patients for adenoid cystic carcinoma of the trachea and the others for large cell carcinoma of the trachea, thyroid cancer and tuberculous granuloma, respectively. Prosthetic reconstruction of the trachea was performed in 4 patients. Carinal resection was performed in 8 patients: With right sleeve pneumonectomy in 4 patients, with right upper lobectomy in 2 patients and only carinal resection in 2 patients. Prosthetic reconstruction after the carinal resection was performed using 3 straight types, 1 curved type and 4 bifurcated types. With regard to the complications of the prosthetic reconstruction, dehiscence at the anastomotic site was seen in 5 patients, granulation in 4 patients, empyema in 3 patients, massive hemorrhage in 2 patients and migration of the prosthesis in 1 patient. Five patients survived more than 1 year. The longest survival time was 43 months. To prevent complications of the prosthetic reconstruction, we improved the anastomotic method, reinforced the anastomotic site with Marlex mesh and protected the surrounding vessels with Lyodura.

Adult↗
PubMed1986

Accumulated strain mechanism for length determination of thick filaments in skeletal muscle. I. Experimental bases.

The kinetics of dissociation of myosin from both ends of thick filaments in glycerinated skeletal muscle fibres and myofibrils was studied in the presence of MgATP by use of an optical diffraction method and phase-contrast microscopy. The dissociation velocity, v (identical to -dL/dt where L is the length of thick filaments at time t), increased with increasing KCl concentration (0.225 to 0.5 M), or increasing pH (6.5 to 8.0) but hardly changed with temperature (5 and 25 degrees C), micromolar concentrations of Ca2+ or sarcomere length (2.4 and 2.75 micron). Over a wide range of filament length, the dissociation velocity could be expressed by v0exp(alpha L), where v0 and alpha are positive constants depending upon the dissociation condition. When the effects of crossbridge formation are minimized it was thus shown that the structural stability of thick filaments in a muscle fibre and a myofibril gradually decreases from the central part to the tips of the filaments. On the basis of these results we propose that the length of thick filaments is largely regulated by an accumulated strain mechanism in which the free energy of association of myosin molecules increases with filament length.

Animals↗
PubMed1985

Does actin bind to the ends of thin filaments in skeletal muscle?

We examined whether or not purified actin binds to the ends of thin filaments in rabbit skeletal myofibrils. Phase-contrast, fluorescence, and electron microscopic observations revealed that actin does not bind to the ends of thin filaments of intact myofibrils. However, in I-Z-I brushes prepared by dissolving thick filaments at high ionic strength, marked binding of actin to the free ends, i.e., the pointed ends, of thin filaments was observed when actin was added at an early phase of polymerization. As the polymerization of actin proceeded, the binding efficiency decreased. The critical actin concentration for this binding was higher than that for polymerization in solution. The binding of G-actin was not observed at low ionic strength. On the basis of these results, we suggest that a particular structure suppressing the binding of actin is present at the free ends of thin filaments in intact myofibrils and that a part of the end structure population is eliminated or modified at high ionic strength so that further binding of actin becomes possible. The myofibril and I-Z-I brush appear to be useful systems for studies aimed at elucidating the organizational mechanisms of actin filaments in vivo.

Actins↗
PubMed1985

Characterization of beta-actinin: a suppressor of the elongation at the pointed end of thin filaments in skeletal muscle.

We examined the physico-chemical properties and the functions of beta-actinin by using a beta-actinin preparation having the same properties as those reported by Maruyama et al. (J. Biochem. 81, 215-232, 1977). beta-Actinin was composed of two components with molecular weights (estimated by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis) of 35,000 and 31,000 daltons. Their isoelectric points in 8 M urea were, respectively, 5.9 and 5.4, clearly distinguishable from those of tropomyosin, troponin T and some enzymes having similar molecular weights. beta-Actinin suppressed the polymerization of actin onto the free end, i.e., the pointed end, of thin filaments in an I-Z-I brush prepared by dissolving thick filaments of a myofibril at high ionic strength. Further, beta-actinin suppressed the association of actin to the whole region of an I-Z-I brush. The present study indicates that beta-actinin is composed of two components and functions as a suppressor of elongation at the pointed end of thin filaments, supporting the conclusions of Maruyama et al. (J. Biochem. 81, 215-232, 1977).

Actinin↗