The MAS-encoded processing protease of yeast mitochondria. Overproduction and characterization of its two nonidentical subunits.

The amino-terminal presequences of proteins imported from the cytoplasm across the mitochondrial inner membrane are cleaved off by a soluble matrix-localized protease composed of two nonidentical homologous subunits. In the yeast Saccharomyces cerevisiae, these are encoded by the nuclear MAS1 and MAS2 genes. We have now constructed yeast strains in which either one or both of the genomic MAS genes are controlled by a galactose-inducible strong promoter.

Involvement of the silencer and UAS binding protein RAP1 in regulation of telomere length.

The yeast protein RAP1, initially described as a transcriptional regulator, binds in vitro to sequences found in a number of seemingly unrelated genomic loci. These include the silencers at the transcriptionally repressed mating-type genes, the promoters of many genes important for cell growth, and the poly[(cytosine)1-3 adenine] [poly(C1-3A)] repeats of telomeres. Because RAP1 binds in vitro to the poly(C1-3A) repeats of telomeres, it has been suggested that RAP1 may be involved in telomere function in vivo.

Porin from Thiobacillus versutus.

The porin of Thiobacillus versutus IFO 14567 was isolated by extraction of cell-envelopes with sodium dodecyl sulfate. It exhibited strong porin-activity after reconstitution into artificial lipid bilayer membranes. The diameter of the pore was determined as 1.

Cholesterol and lipid disturbances in renal disease: the natural history of uremic dyslipidemia and the impact of hemodialysis and continuous ambulatory peritoneal dialysis.

Lipid abnormalities have been postulated to contribute to renal insufficiency by a mechanism that is analogous to atherogenesis. The majority of patients treated for chronic renal failure die of cardiovascular complications. Lipid abnormalities in this group are thought to contribute to this high mortality.

Fall of cholesterol with time on dialysis: impact on atherogenicity.

The majority of patients treated for chronic renal failure die from cardiovascular complications. Lipid abnormalities in this group are thought to contribute to this high mortality. The authors have shown that hemodialysis patients with longer months on dialysis tend to have lower total cholesterol (TC) levels.

Rapid isolation of OmpF porin-LPS complexes suitable for structure-function studies.

A gentle and rapid isolation procedure is described yielding fractions containing better than 95% pure OmpF porin of Escherichia coli BE with different amounts of bound lipopolysaccharide (LPS). The procedure employs continuous free-flow electrophoresis (FFE) in the presence of detergent above its critical micelle concentration. Total yields of around 45% were typically obtained when porin-enriched membrane extracts were processed.

Purification and characterization of yeast anthranilate phosphoribosyltransferase.

Anthranilate phosphoribosyltransferase from Saccharomyces cerevisiae has been purified to homogeneity from an overproducing strain. Analytical ultracentrifugation demonstrated that the enzyme is a dimer of Mr = 83,000 +/- 4,000 (S20.w = 4.

Variability of peritoneal clearances for apolipoprotein and its relationship to susceptibility for atherosclerotic changes in CAPD.

Apolipoprotein Clearance and Atherogenicity in CAPD: Protein and lipoprotein loss is one of the disadvantages of CAPD. The impact of these losses on serum constituents is not fully understood. Lipoprotein disorders are observed in patients with chronic or acute renal failure or undergoing dialytic therapy with resultant increase in atherosclerotic clinical events yet these phenomenon are poorly understood, underinvestigated and underreported.

Native mitochondrial creatine kinase forms octameric structures. II. Characterization of dimers and octamers by ultracentrifugation, direct mass measurements by scanning transmission electron microscopy, and image analysis of single mitochondrial creatine kinase octamers.

Electron micrographs of negatively stained and metal-shadowed mitochondrial creatine kinase (Mi-CK) molecules purified as described by Schlegel et al. (Schlegel, J., Zurbriggen, B.

Lipids in diabetic and nondiabetic hemodialysis and CAPD patients.

To examine the question of "accelerated atherogenesis" in ESRD patients, the authors conducted a lipid survey among their hemodialysis and CAPD populations and evaluated data relevant to the lipid and diabetic status of these groups. Interestingly, longer duration of hemodialysis in nondiabetic patients was associated with lower cholesterol but not HDL, which may reflect diminished cardiac risk and mortality in the long-term survivors. Diabetic patients showed lower HDL but no cholesterol change with longer duration on hemodialysis.

RNA11 protein is associated with the yeast spliceosome and is localized in the periphery of the cell nucleus.

The yeast rna mutations (rna2 through rna10/11) are a set of temperature-sensitive mutations that result in the accumulation of pre-mRNAs at the nonpermissive temperature. Most of the yeast RNA gene products are involved in and essential for mRNA splicing in vitro, suggesting that they code for components of the splicing machinery. We tested this proposal by using an in vitro-synthesized RNA11 protein to complement the temperature-sensitive defect of the rna11 extract.

Widespread distribution of the c-src gene product in nerve cells and axon terminals in the adult rat brain.

The regional and cellular distribution of the proto-oncogene product pp60c-src, a member of the family of membrane-associated tyrosine-specific protein kinases, was analysed in adult rat brain. High-resolution SDS-PAGE allowed analysis of both the 'fibroblast' 60-kDa form and a variant, 61-kDa neuron-specific form of the c-src gene product which is encoded by an alternately processed c-src mRNA. Studies of microdissected brain regions showed that all CNS regions contained both forms of the enzyme, the 61-kDa form predominating in most regions with high content of gray matter and high density of synapses.

Characterization of the altered form of the c-src gene product in neuronal cells.

The pp60c-src protein that is expressed at high levels in cultures of neurons from rat embryos displays an altered mobility on SDS-polyacrylamide gels due to a structural difference in the amino-terminal region of the molecule. In this report we show that the expression of this unique form of pp60c-src, designated pp60c-src(+), is not restricted to cultured neuronal cells since the pp60c-src molecules expressed in tissues from avian and rat neural tissues also display a retarded electrophoretic mobility. The amino-terminal region from pp60c-src(+) was found to contain a novel phosphorylated tryptic peptide that contains phosphoserine.

Splicing of yeast nuclear pre-mRNA in vitro requires a functional 40S spliceosome and several extrinsic factors.

We have previously shown that extracts prepared from most of the yeast temperature-sensitive rna mutants are heat sensitive for pre-mRNA splicing in vitro, and that the products of the corresponding RNA genes are essential for the early stages of the splicing region. In this report, we demonstrate that most heat-inactivated mutant extracts do not form the spliceosome, suggesting that their gene products are likely to be involved in spliceosome formation. Heat-inactivated rna2 extracts, on the other hand, do form a splicing-dependent 40S complex containing uncleaved pre-mRNA exclusively.

Quaternary structure of ornithine aminotransferase in solution and preliminary crystallographic data.

Ornithine aminotransferase was purified from rat liver and crystallized in the presence of ammonium sulphate and poly(ethylene glycol) (PEG 4000). The crystallographic threefold symmetry observed for the resulting two crystal forms stimulated a re-examination of the enzyme's quaternary structure in solution by analytical ultracentrifugation and chemical cross-linking. The results indicate that the oligomeric state or ornithine aminotransferase, under conditions similar to those used in crystallization experiments, is a hexamer (Mr = 256,000) rather than a tetramer or higher oligomers as reported previously.

Changes in the pattern of expression of pp60c-src in cerebellar mutants of mice.

Cultures of neurons from rat embryos have been shown previously to express high levels of a unique form of pp60c-src [Brugge et al (1985): Nature 316:524-526], the cellular homologue of the transforming protein of Rous sarcoma virus. This altered form of pp60c-src, designated pp60c-src(+), displays a retarded electrophoretic mobility due to a structural alteration within the aminoterminal region of the molecule [Brugge et al, 1985]. In order to investigate the distribution and possible role of pp60c-src(+) in intact brain, we have examined the expression of pp60c-src(+) in extracts from developing cerebella from wild-type mice and mutant mice that display progressive degeneration of specific classes of cerebellar neurons.

The yeast RNA gene products are essential for mRNA splicing in vitro.

The yeast rna mutations (rna2-rna11) are a set of temperature-sensitive mutations that result in the accumulation of intron-containing mRNA precursors at the restrictive temperature. We have used the yeast in vitro splicing system to investigate the role of products of the RNA genes in mRNA splicing. We have tested the heat lability of the in vitro mRNA splicing reaction in extracts isolated from mutant and wild-type cells.

Characterization of dimer subunits of intermediate filament proteins.

The fundamental subunit of the various types of intermediate-sized filaments (IF) has been shown to be a tetramer that is thought to represent a double dimer, i.e. an array of two laterally packed coiled-coils of alpha-helices.

Identification of yeast mutants with altered telomere structure.

The chromosomes of the yeast Saccharomyces cerevisiae terminate in a tract of simple-sequence DNA [poly(C1-3A)] that is several hundred base pairs long. We describe the identification of mutant yeast strains that have telomeric tracts that are shorter than normal. A genetic analysis of these strains indicates that these short telomeres are the result of single nuclear recessive mutations and that these mutations can be classified into two different complementation groups.

Investigations of the expression of the cellular src gene product.

We have examined the expression of the c-src gene product in a variety of embryonic and adult tissues, in peripheral blood cells, and in cells transformed by other tumor viruses, in an attempt to identify the types of cells in which pp60c-src might provide a specific function. These studies have indicated that c-src gene expression is regulated at multiple levels in different cell types and have suggested that pp60c-src is not exclusively involved in the regulation of cell proliferation. The lowest levels of pp60c-src were found in fibroblasts, which have previously served as the standard cell type for comparisons between pp60c-src and pp60v-src.

Long poly(A) tracts in the human genome are associated with the Alu family of repeated elements.

Long poly(dA).poly(dT) tracts (poly(A) tracts), regions of DNA containing at least 20 contiguous dA residues on one strand and dT residues on the complementary strand, are found in about 2 X 10(4) copies interspersed throughout the human genome. Using poly(dA).

Structure and interactions of heparan sulfate proteoglycans from a mouse tumor basement membrane.

Various forms of heparan sulfate proteoglycan were solubilized from the mouse Engelbreth-Holm-Swarm (EHS) sarcoma by extraction with 0.5 M NaCl, collagenase digestion and extraction with 4 M guanidine. They could be separated into high (greater than or equal to 1.

HLA antigens in White and Black South African diabetics.

The HLA A and B specificities in 72 Whites with type 1 or juvenile-onset diabetes mellitus (JOD), 53 Blacks with type 1 diabetes or JOD and 52 Blacks with type II or maturity-onset diabetes (MOD) were determined and compared with those in 278 Whites and 311 Blacks who were not diabetic. In Whites with JOD, frequencies of HLA A1 and B8 antigens were significantly increased, whereas those of the A3 and B17 antigens were reduced. Blacks with JOD had an increased frequency of HLA B8.

Shape and stability of fibronectin in solutions of different pH and ionic strength.

At low ionic strength (0.05 M) the sedimentation coefficient of monomeric plasma fibronectin was found to vary from 8S, at pH 3 and 11, to 13.5S at neutral pH.