Purealin, a novel stabilizer of smooth muscle myosin filaments that modulates ATPase activity of dephosphorylated myosin.

Effects of purealin isolated from a sea sponge, Psammaplysilla purea, on the enzymatic and physiochemical properties of chicken gizzard myosin were studied. At 0.15 M KCl, 40 microM purealin increased the Ca2+- and Mg2+-ATPase activity of dephosphorylated gizzard myosin to 2.

Acrosomal actin bundles of Asian and American horseshoe crab sperm differ in protein composition.

Acrosomal actin bundles were isolated from the sperm of horseshoe crabs from four different sources, three from Asia and one from North America, and their protein constituents and structures were compared. The bundle from the American Limulus polyphemus sperm was composed of actin and two associated proteins of MW 95,000 and MW 52,000, as reported previously (Tilney, L. G.

Amino acid sequence of vitamin D-dependent calcium-binding protein from bovine cerebellum.

The amino acid sequence of vitamin D-dependent calcium-binding protein from bovine cerebellum has been determined. It is composed of 260 amino acid residues and its N-terminus is acetylated. The molecular mass is calculated to be 29 851 Da.

Ca2+-independent gizzard myosin light chain kinase produced by cross-linking of the enzyme with calmodulin using glutaraldehyde.

Cross-linked complex of gizzard myosin light chain kinase (MLCK) and calmodulin (CM) was produced by glutaraldehyde treatment of a mixture of these proteins in a high Ca2+ (0.1 mM) solution. Although the specific activity was reduced, this complex showed MLCK activity in a Ca2+-independent manner, different from the original MLCK whose activity was Ca2+-dependent.

Purification of vitamin D-dependent 28,000-Mr calcium-binding protein from bovine cerebellum and kidney by calcium-dependent elution from DEAE-cellulose DE-52 column chromatography.

A vitamin D-dependent calcium-binding protein of 28,000 Mr was purified by a convenient method from the high-ammonium sulfate-saturated fraction (70 to 100% saturation) of bovine cerebellum and kidney. This method is based on the calcium-dependent DEAE-cellulose column chromatography that reflected the specific feature of this protein: different eluting salt concentrations in the presence or absence of Ca2+. The procedure of purification was easily performed by the detection of calcium-binding protein using 45Ca autoradiography.

Enhancement of actin-activated myosin ATPase by an 84K Mr actin-binding protein in vertebrate smooth muscle.

A Ca2+-dependent actin-severing 84K Mr protein prepared from bovine aorta caused four-fold activation of smooth muscle actin-activated myosin ATPase at a 1/10(2) molar ratio to actin in the presence of tropomyosin and light chain kinase-calmodulin in a Ca2+-dependent manner, while it inhibited it markedly at a 1/5 molar ratio. Purified actin-tropomyosin filaments under the experimental ATPase conditions were distributed in a range of more than 10 micron in length and the addition of the 84K Mr protein changed the filament length to around 1 micron at a 1/10(2) molar ratio to actin or less than 50 nm at a 1/5 molar ratio in the presence of Ca2+. However, the apparent length of actin filaments alone does not appear to be responsible for the activation of ATPase activity, since in the absence of tropomyosin, the ATPase activation was much less in spite of actin filament length changes.

Association of chicken pectoralis muscle phosphorylase with the Z-line and the M-line of myofibrils: comparison with 'amorphin', the amorphous component of the Z-line.

By immunofluorescence technique, glycogen phosphorylase, one of the soluble glycolytic enzymes, was shown to be localized in the Z-line of chicken pectoralis muscle myofibrils, in addition to the M-line, as previously reported by Heizmann, C.W. and Eppenberger, H.

High molecular weight calcium binding protein in the microsome of scallop striated muscle.

In the microsome of scallop adductor striated muscle, 30K, 55K, 90K, and 360K proteins were detected as calcium binding proteins by 45Ca autoradiography on the transferred nitrocellulose membrane after sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE). The 360K protein was directly extracted with Triton X-100 from the whole homogenate of striated portion of scallop adductor muscle and purified through DEAE cellulose and hydroxyapatite column chromatography. This purified scallop high molecular weight calcium binding protein (SHCBP) showed a faster mobility in SDS PAGE in the presence of Ca2+ than in its absence.

A simple and rapid method to remove light chain phosphatase from chicken gizzard myosin.

A simple and rapid method to remove myosin light chain phosphatase from gizzard myosin using hydroxyapatite chromatography was developed. Stable phosphorylated myosin without light chain phosphatase and kinase was also prepared by the same procedure. A convenient method using the urea gel system to detect minor contamination by phosphatase of myosin is also described.

The trend of acquired immunity with live poliovirus vaccine and the effect of revaccination: follow-up of vaccinees for ten years.

The persistence of neutralizing antibody (NA) against three types of poliovirus acquired after two doses of trivalent live attenuated poliovirus vaccine (LPV) has been followed up for ten years in individual vaccinees. Sixty-seven children were bled once a year over a five year period following the primary vaccination. More than 80% of them retained NA against all three types of poliovirus.

Purification and some properties of porcine kidney tropomyosin.

A tropomyosin has been purified from porcine kidney and its properties compared with those of rabbit skeletal muscle tropomyosin. Kidney tropomyosin was separated from contaminating vascular smooth muscle tropomyosin by hydroxylapatite chromatography. Kidney tropomyosin resembles tropomyosin from other non-muscle cells in regard to subunit size, mobility on SDS-polyacrylamide gels in the presence and absence of 6 M urea, amino acid composition and morphology.

Regulatory mechanism in smooth muscle: actin-linked regulation.

Our view about the Ca regulation of smooth muscle contraction can be summarized as follows: the regulatory system is actin-linked and consists of tropomyosin and leiotonin; the latter is a complex of two proteins, leiotonin A, the regulatory moiety, and leiotonin C, the Ca-binding moiety. Leiotonin resembles troponin in some respects, but is clearly different in that it has no affinity for tropomyosin and is effective at a leiotonin/actin molar ratio of less than 1:50. The methods of preparing leiotonin were critically reviewed and a suggestion was provided for the development of a new procedure.

The quaternary structure of DNA-dependent RNA polymerase.

The crystals of RNA polymerase of T. thermophilus were examined by electron microscopic observation of the negatively stained and sectioned materials. Three types of crystals were observed: ordered aggregates (Type I), cylindrical duplei (Type II), and plane (Type III) forms.

Quantitative analysis of the mechanism of negative staining with native collagen fibrils and polar tropomyosin paracrystals.

The mechanism of formation of the negatively stained image in electron microscopy was infestigated with native collagen fibrils as a model. The negatively stained image was simulated from the primary structure by using the values of volume or bulkiness of each amino acid residue as a parameter for stain-excluding capacity. The pattern simulated from the bulkiness values gave an excellent fit with the negatively stained image.

Electron microscopic analysis of tropomyosin paracrystals.

Negatively stained images of divalent cation-induced tropomyosin paracrystals show polymorphic patterns which are almost bipolar. Although these bipolar forms are naturally due to antiparallel arrays of molecules, the precise molecular arrangements have not been clarified yet except in the case of one type of these polymorphic paracrystals by Stewart and McLachlan [(1976) J. Mol.

Involvement of an acidic protein in regulation of smooth muscle contraction by the tropomyosin-leiotonin system.

An acidic Ca-binding protein of about 18,000 dalton, different from both modulator protein and troponin C, was found to be involved in the regulatory mechanism of smooth muscle contraction by the tropomyosin-leiotonin system.

Optical diffraction analysis of electron microscope images of tubular structures found in cells infected with herpes simplex virus type 2.

Optical diffraction analysis was done on the electron micrographs of tubular structures found in cells infected with herpes simplex virus type 2. By this method, the helical arrangement of subunits forming a tubular structure was demonstrated.

Characteristics of Ca2+- and Mg2+-induced tension development in chemically skinned smooth muscle fibers.

Chemically skinned fibers from guinea pig taenia caecum were prepared by saponin treatment to study the smooth muscle contractile system in a state as close to the living state as posible. The skinned fibers showed tension development with an increase of Ca2+ in the solution, the threshold tension occurring as 5 X 10(-7) M Ca2+. The maximal tension induced with 10(-4) M Ca2+ was as large and rapid as the potassium-induced contracture in the intact fibers.