Multiple phosphorylation sites of rat liver glycogen synthase

Rat liver glycogen synthase was purified to homogeneity by an improved procedure that yielded enzyme almost exclusively as a polypeptide of Mr 85,000. The phosphorylation of this enzyme by eight protein kinases was analyzed by cleavage of the enzyme subunit followed by mapping of the phosphopeptides using polyacrylamide gel electrophoresis in the presence of SDS, reverse-phase high-performance liquid chromatography and thin-layer electrophoresis. Cyclic AMP-dependent protein kinase, phosphorylase kinase, protein kinase C and the calmodulin-dependent protein kinase all phosphorylated the same small peptide (approx. 20 amino acids) located in a 14 kDa CNBr-fragment (CB-1). Calmodulin-dependent protein kinase and protein kinase C also modified second sites in CB-1. A larger CNBr-fragment (CB-2) of approx. 28 kDa was the dominant site of action for casein kinases I and II, FA/GSK-3 and the heparin-activated protein kinase. The sites modified were all localized in a 14 kDa species generated by trypsin digestion. Further proteolysis with V8 proteinase indicated that FA/GSK-3 and the heparin-activated enzyme recognized the same smaller peptide within CB-2, which may also be phosphorylated by casein kinase 1. Casein kinase 1 also modified a distinct peptide, as did casein kinase II. The results lead us to suggest homology to the muscle enzyme with regard to CB-1 phosphorylation and the region recognized by FA/GSK-3, which in rabbit muscle is characterized by a high density of proline and serine residues. A striking difference with the muscle isozyme is the apparent lack of phosphorylations corresponding to the muscle sites 1a and 1b. These results provide further evidence for the presence of liver- and muscle-specific glycogen synthase isozymes in the rat. That the isozymes differ subtly as to phosphorylation sites may provide a clue to the functional differences between the isozymes.     

The role of sodium restriction in the management of hypertension

More than 50 studies have investigated the effect of altered sodium intake on blood pressure. A regression line drawn through the change in blood pressure and change in sodium intake indicates that blood pressure alters about 10 mmHg (1 mmHg = 133.322 Pa) for every 100 mmol/day alteration in sodium intake, a change similar to that observed in between-population "studies." The studies that have failed to show a change in blood pressure have usually been in people with a blood pressure less than 130/90 mmHg. Normotensive people appear to tolerate a higher intake of sodium before blood pressure rises, but if increased sufficiently, blood pressure rises in most people. Sodium restriction reduces blood pressure in people with severe hypertension, moderate hypertension and mild hypertension. It may be the cause of blood pressure increase associated with age and the reason for the higher prevalence of hypertension and vascular disease in Western communities. Sodium restriction should be used to treat people with elevated blood pressure.     

Detection of the intracellular ras p21 oncogene product by flow cytometry

Rapid identification of the expression of oncogene products in specific cell types could potentially be useful in the diagnosis and treatment of human malignancy. We have now observed that through the use of lysolecithin permeabilization and fluorescence-activated flow cytometry, cells expressing high levels of the v-Ha-ras oncogene product, p21, can readily be distinguished from the nontransformed parent cells in a rapid and quantitative manner.     

Dual fluorochrome analysis of human B lymphocytes: phenotypic examination of resting, anti-immunoglobulin stimulated, and in vivo activated B cells

B cell-enriched preparations were prepared from human peripheral blood and lymphoid tissues by the depletion of T cells and monocytes. Only B cells by virtue of their staining with anti-B1 conjugated to fluorescein were additionally examined. Dual fluorescence staining and flow cytometric analysis demonstrated that the majority of "resting" human peripheral blood and splenic B cells co-express the B cell-restricted B1 and B2 antigens and lack B5, a B cell-restricted activation antigen, and interleukin 2 receptor (IL 2R). In contrast, nearly 2/3 and 1/3 of B1+ cells isolated from lymph node expressed IL 2R and B5 antigens, respectively. When B1+ B cells from peripheral blood and spleen were "activated" by anti-Ig, they lost the B2 antigen and acquired the B5 and/or IL 2R antigens. 2/3 of B1+ cells strongly expressed IL 2R, and up to 1/2 of B1+ cells co-expressed B5. Delineation of increased numbers of B1+ cells that co-express B5 and/or IL 2R within lymphoid tissues obtained from patients with diseases characterized by "activated" B cells provides in vivo confirmation that these phenotypic changes correlate with B cell activation. We believe that the identification and isolation of these and similar subsets of cells defined by differing cell surface phenotypes should further our understanding both of normal B cell activation and the pathophysiology of B cell disease states.     

Description of Dolichodorus cobbi n. sp. (Nematoda: Dolichodoridae) with Description of Dolichodorus cobbi n. sp. (Nematoda: Dolichodoridae) with Morphometrics and Lectotype Designation of D. heterocephalus Cobb, 1914

Dolichodorus cobbi n. sp. is described and illustrated from soil around roots of "woods" on the Stanley Farm, Scott County, Arkansas. This species is distinguishable from others of the genus by its short tail projection. It is most closely related to D. marylandicus but differs in having a short tail projection, longer stylet, greater body length, larger c value, and also in position of excretory pore. A limited number of Cobb''s original specimens and drawings of D. heterocephalus were examined. A lectotype and paralectotype were designated to establish the taxonomic base for the genus. Cobb''s original modified labeled drawing of D. heterocephalus is also included. Morphometric data on D. heterocephalus from the type locality and several other populations are given. Some variations in female tail shape, body length, and stylet length were noted.     

Binding specificity of the periplasmic oligopeptide-binding protein from Escherichia coli.

The structural properties required for the binding of peptide substrates to the Escherichia coli periplasmic protein involved in oligopeptide transport were surveyed by measuring the ability of different peptides to compete for binding in an equilibrium dialysis assay with the tripeptide Ala-Phe-[3H]Gly. The protein specifically bound oligopeptides and failed to bind amino acids or dipeptides. Acetylation of the peptide amino terminus of (Ala)3 severely impaired binding, whereas esterification of the carboxyl terminus significantly reduced but did not completely eliminate binding. Peptides composed of L-amino acids competed more effectively than did peptides containing D-residues or glycine. Experiments with a series of alanyl peptide homologs demonstrated a decrease in competitive ability with increasing chain length beyond tripeptide. Competition studies with tripeptide homologs indicated that a wide variety of amino acyl side chains were tolerated by the periplasmic protein, but side-chain composition did affect binding. Fluorescence emission data suggested that this periplasmic protein possesses more than one substrate-binding site capable of distinguishing peptides on the basis of amino acyl side chains.     

Hormonal and developmental regulation of expression of the hepatic microsomal steroid 16 alpha-hydroxylase cytochrome P-450 apoprotein in the rat

The hormonal regulation of the sexually differentiated cytochrome P-450 isozyme which catalyzes 16 alpha-hydroxylation of testosterone and 4-androstene-3,17-dione in male rat liver (P-450(16) alpha) was investigated. Estradiol valerate injection of male rats caused a decrease in P-450(16) alpha levels to almost the female level, while methyltrienolone injection had the reverse effect in female animals. Hypophysectomy abolished the sex difference in P-450(16) alpha levels. Human growth hormone infusion into male rats, mimicking the female pattern of growth hormone secretion, caused a feminization of P-450(16) alpha levels. The same effect was also seen in hypophysectomized rats of both sexes. In contrast, a different administration schedule involving 12 h injections of human growth hormone, mimicking the male pattern of growth hormone secretion, caused a masculinization of P-450(16) alpha levels in hypophysectomized rats, at a daily dose which causes feminization when given by infusion. Thus, the level of expression of P-450(16) alpha in the liver is dependent on the temporal pattern of blood growth hormone levels. While infusion of rat growth hormone into male rats also feminized the P-450(16) alpha levels, infusion of ovine prolactin had no effect. Ontogenic studies showed that the developmental pattern of P-450(16) alpha expression in the liver coincided with the known pattern of development of the sexual differentiation of hepatic steroid 16 alpha-hydroxylase activity and of the diurnal pattern of growth hormone secretion.     

Selective oxidative destruction of iron-sulfur clusters. Ferricyanide oxidation of Azotobacter vinelandii ferredoxin I

The destructive oxidation of aerobically isolated 7Fe Azotobacter vinelandii ferredoxin I [(7Fe)FdI] by Fe(CN)3-6 is examined using low-temperature magnetic circular dichroism (MCD) and EPR. The results demonstrate that oxidation of the [3Fe-3S] cluster occurs only after essentially complete destruction of the [4Fe-4S] cluster. It is therefore feasible by controlled Fe(CN)3-6 oxidation to obtain a partially metallated form of FdI, (3Fe)FdI, containing only a [3Fe-3S] cluster. The MCD and EPR data demonstrate that the [3Fe-3S] cluster in (3Fe)FdI is essentially identical in structure to that in the native protein.     

Steady flow visualization in a rigid canine aortic cast

Steady flow studies were conducted in a transparent canine aortic cast. The cast segment stretched from the aortic valve to beyond the renal arteries and included all major branches. Flow was visualized by analysis of dye streaklines. Flow rates for basal and exercising cardiovascular states were simulated. The Reynolds numbers in the ascending aorta for basal and exercising conditions were 900 and 1587 respectively. Aortic core flow was laminar in basal simulations. Disturbed flow commenced in the upper descending aorta with exercising flow rates. Separation zones existed along the inner curvature of the aortic arch and the proximal walls of the brachiocephalic, left subclavian, and coeliac arteries. Such zones may exist over a portion of the cardiac cycle. If either renal artery was occluded, then a vortex formed. This vortex is associated with high shear regions which correlate well with sites where sudanophilic lesions have been reported in cholesterol-fed nephrectomized rabbits.     

Purification and characterization of a periplasmic oligopeptide binding protein from Escherichia coli

We have purified and characterized an oligopeptide binding protein released from the periplasm of Escherichia coli W by mild osmotic shock. The purified protein was greater than 97% homogeneous as determined by either sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Mr = 60,000) or isoelectric focusing (pI = 5.95). The binding protein has a Stokes radius of 30 A and a sedimentation coefficient (s(0)20,w) of 4.6 S. Based on these hydrodynamic studies, the native protein has a molecular weight of 56,000. The tripeptide, Ala-Phe-[3H]Gly, which is transported via the shock-sensitive sensitive oligopeptide permease, binds to the purified protein in dilute solution with a Kd of 0.1 microM and a stoichiometry of approximately 1 to 1. Results from this study support the hypothesis that this periplasmic oligopeptide binding protein functions in the initial recognition of peptide substrates for the oligopeptide permease system.