Arabidopsis PEX19 is a dimeric protein that binds the peroxin PEX10.

Peroxisomes are organelles found in all eukaryotic cells. Peroxisomes import integral membrane proteins post-translationally, and PEX19 is a predominantly cytosolic, farnesylated protein of mammalian and yeast cells that binds multiple peroxisome membrane proteins and is required for their correct targeting/insertion to the peroxisome membrane. We report the characterisation of the Arabidopsisthaliana homologue of PEX19 which is a predominantly cytosolic protein.

Characterization of the targeting signal of the Arabidopsis 22-kD integral peroxisomal membrane protein.

Using a combination of in vivo and in vitro assays, we characterized the sorting pathway and molecular targeting signal for the Arabidopsis 22-kD peroxisome membrane protein (PMP22), an integral component of the membrane of all peroxisomes in the mature plant. We show that nascent PMP22 is sorted directly from the cytosol to peroxisomes and that it is inserted into the peroxisomal boundary membrane with its N- and C-termini facing the cytosol. This direct sorting of PMP22 to peroxisomes contrasts with the indirect sorting reported previously for cottonseed (Gossypium hirsutum) ascorbate peroxidase, an integral PMP that sorts to peroxisomes via a subdomain of the endoplasmic reticulum.

Secretory bulk flow of soluble proteins is efficient and COPII dependent.

COPII-coated vesicles, first identified in yeast and later characterized in mammalian cells, mediate protein export from the endoplasmic reticulum (ER) to the Golgi apparatus within the secretory pathway. In these organisms, the mechanism of vesicle formation is well understood, but the process of soluble cargo sorting has yet to be resolved. In plants, functional complements of the COPII-dependent protein traffic machinery were identified almost a decade ago, but the selectivity of the ER export process has been subject to considerable debate.

Extensive N-glycosylation reduces the thermal stability of a recombinant alkalophilic bacillus alpha-amylase produced in Pichia pastoris.

Alkalophilic Bacillus alpha-amylase (ABA) was produced in the yeast Pichia pastoris with a yield of 50 mg L(-1) of culture supernatant. The recombinant protein, rABA, was glycosylated at seven of the nine sites for potential N-glycosylation as identified by automated peptide sequencing and MALDI-TOF MS of tryptic fragments. The number of hexose units within each glycan chain was found to vary from 8 to 18 as calculated from the masses of glycosylated peptide fragments.

Saturation of the endoplasmic reticulum retention machinery reveals anterograde bulk flow.

We have studied the possible mechanisms of endoplasmic reticulum (ER) export and retention by using natural residents of the plant ER. Under normal physiological conditions, calreticulin and the lumenal binding protein (BiP) are efficiently retained in the ER. When the ER retention signal is removed, truncated calreticulin is much more rapidly secreted than truncated BiP.

Does root glutamine synthetase control plant biomass production in lotus japonicus L.?

To investigate the contribution of root cytosolic glutamine synthetase (GS) activity in plant biomass production, two different approaches were conducted using the model legume Lotus japonicus. In the first series of experiments, it was found that overexpressing GS activity in roots of transgenic plants leads to a decrease in plant biomass production. Using (15)N labelling it was shown that this decrease is likely to be due to a lower nitrate uptake accompanied by a redistribution to the shoots of the newly absorbed nitrogen which cannot be reduced due to the lack of nitrate reductase activity in this organ.

Reduction of plasma homocyst(e)ine levels by breakfast cereal fortified with folic acid in patients with coronary heart disease.

Background: The Food and Drug Administration (FDA) has recommended that cereal-grain products be fortified with folic acid to prevent congenital neural-tube defects. Since folic acid supplementation reduces levels of plasma homocyst(e)ine, or plasma total homocysteine, which are frequently elevated in arterial occlusive disease, we hypothesized that folic acid fortification might reduce plasma homocyst(e)ine levels.

Methods: To test this hypothesis, we assessed the effects of breakfast cereals fortified with three levels of folic acid, and also containing the recommended dietary allowances of vitamins B6 and B12, in a randomized, double-blind, placebo-controlled, crossover trial in 75 men and women with coronary artery disease.

Overexpression of a soybean gene encoding cytosolic glutamine synthetase in shoots of transgenic Lotus corniculatus L. plants triggers changes in ammonium assimilation and plant development.

A soybean cytosolic glutamine synthetase gene (GS15) was fused with the constitutive 35S cauliflower mosaic virus (CaMV) promoter in order to direct overexpression in Lotus corniculatus L. plants. Following transformation with Agrobacterium rhizogenes, eight independent Lotus transformants were obtained which synthesized additional cytosolic glutamine synthetase (GS) in the shoots.

Efficacy and safety of pravastatin in the treatment of patients with type I or type II diabetes mellitus and hypercholesterolemia.

Purpose: Patients with type I and type II diabetes mellitus have an increased risk of coronary heart disease. In many diabetics, hypercholesterolemia is present and further exacerbates this risk. We investigated the efficacy and safety of pravastatin in the treatment of patients with type I or type II diabetes mellitus and hypercholesterolemia.

Adult onset nesidioblastosis: response of glucose, insulin, and secondary peptides to therapy with Sandostatin.

Adult onset nesidioblastosis (AON) is an extremely rare entity associated with hypersecretion of insulin. Previous reports have demonstrated that the somatostatin analog, Sandostatin (SMS), will control the clinical symptoms induced by infantile nesidioblastosis. We hypothesized that insulin, C-peptide, and secondary peptide secretion from AON is provocable.

Efficacy of bedtime NPH insulin with daytime sulfonylurea for subpopulation of type II diabetic subjects.

Although insulin and sulfonylureas often have additive clinical effects when used in combination for type II (non-insulin-dependent) diabetes, these results are variable and a clinical role for this approach is not yet established. This study tests the efficacy of a specific combined regimen for a subpopulation of patients with a randomized double-masked placebo-controlled crossover design and under conditions similar to those of clinical practice. Twenty subjects with limited duration (less than 15 yr) type II diabetes who were moderately obese (less than 160% ideal wt) and proved imperfectly controlled on 10 mg glyburide twice daily completed two 4-mo crossover protocols, comparing a single injection of NPH insulin in the evening plus 10 mg glyburide in the morning with insulin plus placebo.

Reduction of plasma lipids, lipoproteins, and apoproteins by dietary fish oils in patients with hypertriglyceridemia.

Dietary fish oils, which are rich in omega-3 fatty acids, have been reported to reduce plasma lipid levels in normolipidemic subjects. We examined the effects of fish oil in 20 hypertriglyceridemic patients: 10 with Type IIb hyperlipidemia and 10 with Type V. These patients were put on three diets differing primarily in fatty acid composition and fat content.

Sterol composition of normal human bile. Effects of feeding shellfish (marine) sterols.

To examine the sterol composition of normal human bile and the effects of dietary components from certain shellfish upon bile composition, we fed 7 subjects diets rich in shellfish for 2 wk following a typical American diet. The total cholesterol, bile acid, and phospholipid, and the individual sterols and bile acids of the bile samples during each dietary period were measured. In the bile of 7 subjects consuming the typical American diet, nine different neutral sterols, in addition to cholesterol, were identified.

Colestipol plus nicotinic acid in treatment of heterozygous familial hypercholesterolaemia.

Thriteen patients with heterozygous familial hypercholesterolaemia (FH) were sequentially treated with: a low-cholesterol, fat-restricted diet; diet and colestipol; and diet and colestipol and nicotinic acid. Concentrations of plasma cholesterol decreased from 415 +/- 69 mg/dl on diet alone to 327 +/- 54 mg/dl on colestipol and fell to 246 +/- 49 mg/dl on the combined drug regimen. Plasma concentrations of LDL cholesterol declined 24% on colestipol; the subsequent addition of nicotinic acid resulted in a further 31% fall so that values on the combined drug regimen were 47% below those seen on diet alone.