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Y Nakauchi

Publications and source records attributed to Y Nakauchi.

29 records · Page 2Linked to original sources
PubMed1993

Characterization of beta-connectin (titin 2) from striated muscle by dynamic light scattering.

Connectin (titin) is a large filamentous protein (single peptide) with a molecular mass of approximately 3 MDa, contour length approximately 900 nm, and diameter approximately 4 nm, and resides in striated muscle. Connectin links the thick filaments to the Z-lines in a sarcomere and produces a passive elastic force when muscle fiber is stretched. The aim of this study is to elucidate some aspects of physical properties of isolated beta-connectin (titin 2), a proteolytic fragment of connectin, by means of dynamic light-scattering (DLS) spectroscopy. The analysis of DLS spectra for beta-connectin gave the translational diffusion coefficient of 3.60 x 10(-8) cm2/s at 10 degrees C (or the hydrodynamic radius of 44.1 nm), molecular mass little smaller than 3.0 MDa (for a literature value of sedimentation coefficient), the root-mean-square end-to-end distance of 163 nm (or the radius of gyration of 66.6 nm), and the Kuhn segment number of 30 and segment length of 30 nm (or the persistence length of 15 nm). These results permitted to estimate the flexural rigidity of 6.0 x 10(-20) dyn x cm2 for filament bending, and the elastic constant of 7 dyn/cm for extension of one persistence length. Based on a simple model, implications of the present results in muscle physiology are discussed.

Animals↗
PubMed1992

Autophosphorylation of beta-connectin (titin 2) in vitro.

Phosphorylation of beta-connectin (titin 2), an elastic protein of chicken breast muscle, occurred in the presence of [gamma-32P] ATP, 0.2 mM CaCl2 and 25 mM phosphate buffer, pH 7.0. Addition of 3 mM MgCl2 did not affect the phosphorylation. However, Ca2+ ions were required for the phosphorylation and EGTA inhibited it even if MgCl2 were present. Myosin light chain kinase (gizzard MLCK), cAMP dependent protein kinase (A kinase), and protein kinase C (C kinase) did not phosphorylate beta-connectin in vitro under optimal conditions. Thus it appears that beta-connectin, possibly containing a domain homologous with MLCK, has an autophosphorylating action.

Adenosine Triphosphate↗
PubMed1992

Characterization and localization of alpha-connectin (titin 1): an elastic protein isolated from rabbit skeletal muscle.

A simplified procedure to isolate alpha-connectin (titin 1, TI), a gigantic elastic protein, from rabbit skeletal muscle is described. A rapid column chromatography step to concentrate alpha-connectin is introduced. Separation of alpha-connectin from beta-connectin is introduced. Separation of alpha-connectin from beta-connectin (titin 2, TII) in the presence of 4 M urea at pH 7.0 did not cause any change in the secondary structure of alpha-connectin as judged by circular dichroic spectra. Ultraviolet absorption spectra and the amino acid composition of alpha-connectin (MW, approximately 3 x 10(6)) were similar to those of its proteolytic product, beta-connectin (MW, approximately 2 x 10(6)). Circular dichroic spectra suggested that both alpha- and beta-connectin consist of 60% beta-sheet and 30% beta-turn. It thus appears that the whole elastic filament of connectin has a folded beta-strand structure. Proteolysis of alpha-connectin by calpain resulted in formation of beta-connectin and smaller peptides. The alpha-connectin interacted with both myosin and actin filaments similarly to beta-connectin. Polyclonal antibodies raised against 1200 kDa peptides obtained from aged rabbit skeletal myofibrils reacted with alpha-connectin (titin 1, TI) but only weakly with beta-connectin (titin 2, TII) in rabbit skeletal muscle. Immunoelectron microscopy and indirect immunofluorescence microscopy revealed that the antibodies bound at the Z-line and at the epitope regions in the I-band near the binding site of a monoclonal antibody SM1 whose position depends on sarcomere length. It thus appears that beta-connectin extends from the edge of M-line to the above epitope region in the I-band.

Actins↗
PubMed1991

Structural properties of connectin studied by ultraviolet resonance Raman spectroscopy and infrared dichroism.

Ultraviolet resonance Raman spectra of solubilized connectin indicated the presence of beta-sheets and hydrogen-bonded irregular structures. Some Trp and Tyr sidechains are located in hydrophobic environments and some NHs of mainchain amides and Trp indoles are not easily reached by solvent water, suggesting the presence of folded structures constructed of the beta- and irregular parts. Infrared spectra showed an abundance of beta-sheets in a connectin fiber, some of which were aligned with their mainchain axes parallel to the fiber axis. Thus, the beta-spiral structure proposed for elastin is improbable in connectin. This conclusion is also supported by their different amide III frequencies in the visible Raman spectra. A possible filamentous structure of repeated domains, consisting of beta-sheets and irregular parts, is discussed.

Animals↗
PubMed1989

Binding of connectin to myosin filaments.

Binding of native connectin (2,100 kDa fragment of alpha-connectin) to myosin filaments was investigated using a sedimentation technique and densitometric estimations of the separated proteins. In the presence of 60 mM KCl and 5 mM phosphate buffer, pH 7.0, as much as 1.5 mol of connectin was bound to 1 mol of myosin, suggesting that some 150 connectin filaments bound to a single myosin filament of approximately 0.5 micron in length. This value was much more than the ratio found in muscle (12:1). It appeared that C protein did not affect the binding of connectin to myosin filaments.

Animals↗
PubMedDate not supplied

A case of insulin dependent diabetes mellitus associated with relapsing polychondritis, Hashimoto's thyroiditis and pituitary adrenocortical insufficiency in succession.

The case of a 40 year-old woman with insulin dependent diabetes mellitus associated with relapsing polychondritis, Hashimoto's thyroiditis and pituitary adrenocortical insufficiency in succession, considered as polyglandular autoimmune syndrome type III, is described. The results of this study suggest that relapsing polychondritis and pituitary adrenocortical insufficiency might be included in polyglandular autoimmune syndrome. It is very interesting that in the pathogenicity of polyglandular autoimmune syndrome type III, the elevation of OKT4/OKT8 ratio which indicates the hypofunction of suppressor T cell is shown and that she has HLA DR4 which has a significant relationship with insulin dependent diabetes mellitus in Japanese.

Adrenal Insufficiency↗
PubMedDate not supplied

Systemic lupus erythematosus relapse with lupus cystitis.

A 45-year-old woman who had been diagnosed as having systemic lupus erythematosus (SLE) at the age of 28 years and who had been in remission developed severe urinary frequency, watery diarrhea, vomiting and weight loss. She also developed acute renal failure and her serological examination was consistent with active SLE. She had a markedly decreased urinary bladder capacity of 20 ml with hydroureteronephrosis. Histopathological study of her urinary bladder biopsy specimen showed mucosal edema, infiltration by lymphocytes and granulocytes, and deposition of IgA in the epithelium and submucosal region. We diagnosed this as a case of lupus cystitis. The patient's symptoms were alleviated by bilateral nephrostomy and corticosteroid therapy. In the present episode the patient showed none of the usual symptoms of SLE. This case and others reported in the literature show that lupus cystitis presents with specific signs and symptoms and therefore, this syndrome may represent a specific clinical manifestation of SLE.

Acute Kidney Injury↗