Corrections - Studies on the Soluble 17β-Hydroxysteroid Dehydrogenase from Human Placenta. Evidence for a Subunit Structure

Biochemistry ◽  
1972 ◽  
Vol 11 (6) ◽  
pp. 1122-1122 ◽  
Author(s):  
Joseph Jarabak ◽  
M. Street
Keyword(s):  
Human Placenta ◽  
Hydroxysteroid Dehydrogenase ◽  
Subunit Structure ◽  
A Subunit

Receptive fields of primate retinal ganglion cells studied with a novel technique

1998 ◽  
Vol 15 (1) ◽  
pp. 161-175 ◽  
Author(s):  
BARRY B. LEE ◽  
JAN KREMERS ◽  
TSAIYAO YEH
Keyword(s):  
Ganglion Cells ◽  
Receptive Fields ◽  
Bipolar Cells ◽  
Subunit Structure ◽  
Retinal Ganglion ◽  
Cell Frequency ◽  
Novel Technique ◽  
Large Factor ◽  
A Subunit ◽  
Size Estimates

We have reinvestigated receptive-field structure of ganglion cells of the macaque parafovea using counterphase modulation of a bipartite field. Receptive fields were mapped with luminance, chromatic, and cone-isolating stimuli. Center sizes of middle (M) and long (L) wavelength cone opponent cells of the parvocellular (PC) pathway were consistent with previous estimates (Gaussian radii of 2–4 min of arc, corresponding to center diameters of 6–12 min of arc). We calculate that a large factor of the enlargement relative to cone radius could be blur due to the eye's natural optics. Maps were consistent with cone selectivity in surround mechanisms, which had radii of 5–8 min of arc. For magnocellular (MC) cells, center size estimates were also consistent with grating measurements from the literature (also Gaussian radii of 2–4 min of arc). The surround mechanism contributing the MC-cell frequency-doubled response to chromatic modulation appears to possess a subunit structure, and we speculate it derives from nonlinear summation of signals from M,L-cone opponent subunits, such as midget bipolar cells.

Characterization of the interaction between subunits of the botulinum toxin complex produced by serotype D through tryptic susceptibility of the isolated components and complex forms

Microbiology ◽  
2005 ◽  
Vol 151 (5) ◽  
pp. 1475-1483 ◽  
Author(s):  
Tomonori Suzuki ◽  
Toshihiro Watanabe ◽  
Shingo Mutoh ◽  
Kimiko Hasegawa ◽  
Hirokazu Kouguchi ◽  
...  
Keyword(s):  
Complex Form ◽  
Subunit Structure ◽  
Assembly Model ◽  
Single Form ◽  
Toxin Complex ◽  
A Subunit ◽  
Complex Forms ◽  
The Individual

The 650 kDa large toxin complex (L-TC) produced by Clostridium botulinum serotype D strain 4947 (D-4947) has a subunit structure composed of unnicked components, i.e. neurotoxin (NT), non-toxic non-haemagglutinin (NTNHA) and three haemagglutinin subcomponents (HA-70, HA-33 and HA-17). In this study, subunit interactions were investigated through the susceptibilities of the toxin components to limited trypsin proteolysis. Additionally, complex forms were reconstituted in vitro by various combinations of individual components. Trypsin treatment of intact D-4947 L-TC led to the formation of mature L-TC with nicks at specific sites of each component, which is usually observed in other strains of serotype D. NT, NTNHA and HA-17 were cleaved at their specific sites in either the single or complex forms, but HA-33 showed no sign of proteolysis. Unlike the other components, HA-70 was digested into random fragments as a single form, but it was cleaved into two fragments in the complex form. Based on the relative position of exposed or hidden regions of the individual components in the complex derived from their tryptic susceptibilities, an assembly model is proposed for the arrangement of individual subunits in the botulinum L-TC.

scholarly journals Thiol reduction of human α2-macroglobulin. The subunit structure

1972 ◽  
Vol 127 (1) ◽  
pp. 187-197 ◽  
Author(s):  
J. M. Jones ◽  
J. M. Creeth ◽  
R. A. Kekwick
Keyword(s):  
Molecular Weight ◽  
Large Scale ◽  
Sedimentation Equilibrium ◽  
Subunit Structure ◽  
Experimental Conditions ◽  
A Value ◽  
Α2 Macroglobulin ◽  
A Subunit ◽  
Normal Human ◽  
Ph Range

1. Human α2-macroglobulin was prepared from a fraction obtained during the large-scale separation of normal human plasma proteins for clinical use. 2. Sedimentation-equilibrium measurements indicated a molecular weight of 725000. A value of 18.1S was obtained for s020,w. 3. The dissociation that occurs in the pH range 4.5–2.5 and in the region of neutrality in urea-containing solutions is consistent with a dimeric structure of the molecule. 4. The effects of the thiol reagents mercaptoethanol, mercaptoethylamine and N-acetylcysteine were investigated over a range of experimental conditions. Distinct components having sedimentation coefficients of 15, 12 and 8.5S were identified. 5. Conditions were found under which limited reduction with thiol liberated a subunit with a molecular weight approximately one-quarter of that of the intact molecule. This subunit retains the serological specificity of the whole molecule.

11β-hydroxysteroid dehydrogenase activity (E.C. 1.1.1.146) in human placenta and decidua

1980 ◽  
Vol 13 (9) ◽  
pp. 1081-1087 ◽  
Author(s):  
A.López Bernal ◽  
A.P.F. Flint ◽  
A.B.M. Anderson ◽  
A.C. Turnbull
Keyword(s):  
Dehydrogenase Activity ◽  
Human Placenta ◽  
Hydroxysteroid Dehydrogenase

scholarly journals The composition and proposed subunit structure of egg-white β-ovomucin. The isolation of an unreduced soluble ovomucin

1975 ◽  
Vol 147 (1) ◽  
pp. 55-62 ◽  
Author(s):  
D S Robinson ◽  
J B Monsey
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Sialic Acid ◽  
Sodium Dodecyl ◽  
Egg White ◽  
Disc Electrophoresis ◽  
Subunit Structure ◽  
Sedimentation Analysis ◽  
Guanidinium Chloride ◽  
A Subunit

1. New preparations of reduced carboxymethylated β-ovomucin (S-carboxymethyl-β-ovomucin) were homogeneous by sedimentation analysis, analytical sedimentation to equilibrium in CsCl gradients, and disc electrophoresis in sodium dodecyl sulphate. 2. Degradation of S-carboxymethyl-β-ovomucin with either CNBr or trypsin indicated the presence of a subunit (approx. mol. wt. 112300). 3. Electron microscopy showed that S-carboxymethyl-β-ovomucin consisted of chains of globular units (approx. mol. wt. 103 000). IN 6M-guanidinium chloride S-carboxymethyl-β-ovomucin existed mainly as an aggregate (mol. wt. 720 000). 4. S-Carboxymethyl-β-ovomucin contained ester sulphate (4.24%, W/W) and carbohydrate (60%, W/W), which consisted of large amounts of galactose (22%, W/W), galactosamine (8.9%, W/W) and sialic acid (10.6%, W/W). 5. An unreduced soluble fibrous component (component SGH) extracted from crude ovomucin precipitate with 5M-guanidinium chloride contained β-ovomucin (approx. 70%, W/W). By using the Scheraga-Mandelkern equation the molecular weight of component SGH was calculated to be 11.5 times 10(6).

scholarly journals Subunit structure of junctional feet in triads of skeletal muscle: a freeze-drying, rotary-shadowing study.

1984 ◽  
Vol 99 (5) ◽  
pp. 1735-1742 ◽  
Author(s):  
D G Ferguson ◽  
H W Schwartz ◽  
C Franzini-Armstrong
Keyword(s):  
Three Dimensional ◽  
Freeze Fracture ◽  
Subunit Structure ◽  
Thin Sections ◽  
Large Structures ◽  
Foot Structure ◽  
Freeze Dried ◽  
Thin Sectioning ◽  
En Face ◽  
A Subunit

Isolated heavy sarcoplasmic reticulum vesicles retain junctional specializations (feet) on their outer surface. We have obtained en face three-dimensional views of the feet by shadowing and replicating the surfaces of freeze-dried isolated vesicles. Feet are clearly visible as large structures located on raised platforms. New details of foot structure include a four subunit structure and the fact that adjacent feet do not abut directly corner to corner but are offset by half a subunit. Feet aligned within rows were observed to be rotated at a slight angle off the long axis of the row creating a center-to-center spacing (32.5 nm) slightly less than the average diagonal of the feet (35.3 nm). Comparison with previous information from thin sections and freeze-fracture showed that this approach to the study of membranes faithfully preserves structure and allows better visualization of surface details than either thin-sectioning or negative-staining.

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