Biomedical subjects

J Pletcher

Publications and source records attributed to J Pletcher.

At least 19 recordsLinked to original sources

PubMed1995

Preliminary X-ray studies on two new crystal forms of staphylococcal enterotoxin C2.

Two new crystal forms of staphylococcal enterotoxin C2 have been obtained by vapor-diffusion methods. Form 1 crystals are monoclinic in space group P2(1) with cell dimensions a = 43.43, b = 69.92, c = 42.22 A, 8 = 90.1 degrees and diffract to at least 2.7 A resolution. Form 2 crystals are tetragonal in space group P4(1)2(1)2 or P4(3)2(1)2 with cell dimensions a = b = 42.98, c = 289.92 A and diffract to 1.9 A resolution.

Journal Article↗

PubMed1995

Crystallization and preliminary analysis of two crystal forms of human clara cell 16 kDa protein (CC10).

The human Clara cell 16 kDa protein (CC10), isolated from lung lavage fluid, has been crystallized in two crystal forms. The first is in space group P1 and has cell parameters a = 43.04, b = 45.90, c = 51.29 A and alpha = 62.46, beta = 69.74, gamma = 69.43 degrees. Two molecules are present in the unit cell. The second form is in space group P222, with cell parameters a = 42.24, b = 84.06, c = 40.05 A and alpha = beta = gamma = 90 degrees, and four molecules per unit cell. Its diffraction pattern displays pseudo-body-centered symmetry. Both crystal forms diffract X-rays beyond 2.0 A.

Journal Article↗

PubMed1995

Residues defining V beta specificity in staphylococcal enterotoxins.

The three-dimensional structure of staphylococcal enterotoxin C2 has been determined at 2.7 A resolution by x-ray diffraction, while the structures of enterotoxins A and E have been modelled based on their sequence homology to other staphylococcal enterotoxins. The T-cell receptor-binding sites of staphylococcal enterotoxin (SE) B and SEC2 are compared and the stereochemical interactions likely to be responsible for their differing V beta specificities are identified. A similar comparison is made between SEA and SEE.

Amino Acid Sequence↗

PubMed1994

Structure of a human Clara cell phospholipid-binding protein-ligand complex at 1.9 A resolution.

The Clara cell phospholipid-binding protein, previously referred to as CC10, is a homodimeric protein of M(r) 15,800. It is secreted into the bronchioalveolar lining layer in mammalian lung. A combination of X-ray crystallography and chemical analysis was used to determine that phosphatidylcholine and phosphatidylinositol are bound to the protein as isolated from human lung lavage. We now report the crystal structure of the protein-phospholipid complex at 1.9 A resolution. The phospholipid is bound inside the protein's large hydrophobic cavity. A model is proposed for the manner in which a channel may open to provide access to the cavity, allowing the binding or potential release of phospholipid.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1993

Subset-specific effects of sex hormones and pituitary gonadotropins on human lymphocyte proliferation in vitro.

Clinical observations on patients with systemic lupus erythematosus and rheumatoid arthritis and studies in murine models of autoimmune diseases suggest an important role for the sex and pituitary hormones in immune function. Estrogen and testosterone have been shown to modulate B cell functions in vitro. Prolactin (PRL) has been shown to have immunomodulatory functions. Follicle stimulating hormone (FSH) and luteinizing hormone (LH) have homology to thioredoxin, a potentiator of T-cell growth. We therefore studied the proliferative response of peripheral blood mononuclear cells (PBMC) from normal adult males to various stimuli in the presence or absence of estradiol (E2), testosterone (Te), PRL, FSH, and LH and the effect of these hormones on T-cell subsets by flow cytometry. Unfractionated PBMC were stimulated with 1% phytohemagglutinin (PHA) (polyclonal activation), anti-CD3 (T-cell receptor stimulation), or recombinant interleukin 2 (IL-2) (late stages of activation). We assessed the effects of E2 (0.3-30 ng/ml), Te (3-300 ng/ml), PRL (2-200 ng/ml), FSH (1-100 mIU/ml), and LH (1-100 mIU/ml). E2 and Te had no consistent effect on PBMC proliferation in response to any of the stimuli. E2 significantly decreased the percentage of CD4+ cells following PHA stimulation (P = 0.022), while significantly enhancing the percentage of CD8+ cells following IL-2 stimulation (P = 0.007). Te significantly increased the percentage of CD4+ cells following IL-2 stimulation (P = 0.03). PRL enhanced proliferation in response to IL-2 and PHA without subset-specific effects. FSH and LH both enhanced IL-2-induced proliferation, particularly in physiological doses (10 mIU/ml). FSH at 100 mIU/ml significantly decreased the percentage of CD4+ cells in unstimulated cultures (P = 0.003), while it enhanced the percentage of CD8+ cells following PHA stimulation (P = 0.004). The enhancement in CD8+ cells appeared the most marked in the CD8+CD28+ subset. LH at 10 mIU/ml significantly enhanced the percentage of CD4+ cells following IL-2 stimulation (P = 0.009) and at higher doses (100 mIU/ml) enhanced the percentage of CD4+ cells following PHA stimulation (P = 0.011). Thus, sex steroids and adenohypophyseal hormones (PRL, FSH, and LH) have subset-specific effects on T-cell activation which may influence sex-related differences in immune response.

Adult↗

PubMed1992

Crystal structure of staphylococcal enterotoxin B, a superantigen.

The three-dimensional structure of staphylococcal enterotoxin B, which is both a toxin and a super-antigen, has been determined to a resolution of 2.5 A. The unusual main-chain fold containing two domains may represent a general motif adopted by all staphylococcal enterotoxins. The T-cell receptor binding site encompasses a shallow cavity formed by both domains. The MHCII molecule binds to an adjacent site. Another cavity with possible biological activity was also identified.

Animals↗

PubMed1992

Refined structure of rat Clara cell 17 kDa protein at 3.0 A resolution.

The rat Clara cell 17 kDa protein (previously referred to as the rat Clara cell 10 kDa protein) has been reported to inhibit phospholipase A2 and papain, and to also bind progesterone. It has been isolated from rat lung lavage fluid and crystallized in the space group P6(5)22. The structure has been determined to 3.0 A resolution using the molecular replacement method. Uteroglobin, whose amino acid sequence is 55.7% identical, was used as the search model. The structure was then refined using restrained least-squares and simulated annealing methods. The R-factor is 22.5%. The protein is a covalently bound dimer. Two disulfide bonds join the monomers together in an antiparallel manner such that the dimer encloses a large internal hydrophobic cavity. The hydrophobic cavity is large enough to serve as the progesterone binding site, but access to the cavity is limited. Each monomer is composed of four alpha-helices. The main-chain structure of the Clara cell protein closely resembles that of uteroglobin, but the nature of many of the exposed side-chains differ. This is true, particularly in a hypervariable region between residues 23 and 36, and in the H1H4 pocket.

Amino Acid Sequence↗

PubMed1990

Crystallization and preliminary X-ray study of rat Clara cell 10,000 Mr protein.

Single crystals of Clara cell 10,000 Mr protein have been grown by vapour diffusion in the presence of ammonium sulphate. The space group is P4(1)32 or P4(3)32 with unit cell dimension a = 156.9 A. Crystals diffract to about 3.8 A resolution.

Animals↗

PubMed1988