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Biomedical subjects

A Ghetti

Publications and source records attributed to A Ghetti.

At least 19 recordsLinked to original sources
PubMed1995

In vitro trans-splicing in Saccharomyces cerevisiae.

The interactions established at the 5'-splice site during spliceosome assembly are likely to be important for both precise recognition of the upstream intron boundary and for positioning this site in the active center of the spliceosome. Definition of the RNA-RNA and the RNA-protein interactions at the 5' splice site would be facilitated by the use of a small substrate amenable to modification during chemical synthesis. We describe a trans-splicing reaction performed in Saccharomyces cerevisiae extracts in which the 5' splice site and the 3' splice site are on separate molecules. The RNA contributing the 5' splice site is only 20 nucleotides long and was synthesized chemically. The trans-splicing reaction is accurate and has the same sequence, ATP, and Mg2+ requirements as cis-splicing. We also report how deoxy substitutions around the 5'-splice site affect trans-splicing efficiency.

Actins↗
PubMed1995

Specificity of Prp24 binding to RNA: a role for Prp24 in the dynamic interaction of U4 and U6 snRNAs.

Prp24 was previously isolated as a suppressor of a cold-sensitive U4 mutation and is required for at least the first step of splicing in vitro. Our investigation of the in vitro RNA binding properties of the purified Prp24 protein shows that it binds preferentially to the U4/U6 hybrid snRNAs compared to other snRNAs. The interaction between Prp24 and the U4/U6 hybrid appears to involve two regions in the RNA: the 39-57 region of U6 and stem II of the U4/U6 hybrid. Interestingly, some U4 mutations, which destabilize stem II, increase the affinity of Prp24 for the U4/U6 RNAs compared to the wild type. This suggests that the binding of Prp24 to the U4/U6 RNAs may involve some destabilization of the RNA duplex. We also found that Prp24 can stimulate the annealing of U4 and U6, suggesting that Prp24 participates in both the formation and disassembly of the U4/U6 hybrid during splicing.

Base Sequence↗
PubMed1994

[The risk factors of atherosclerotic disease. Life style and primary prevention].

Atherosclerosis brings about cardiovascular diseases and is the world's largest cause of death. Risk factors are to be considered in their incidence and correlation to various pathologies. Cholesterolaemia, smoking, physical inactivity, alcohol are held to be the most important risk factors. Hypercholesterolaemia involves a greater incidence of coronary heart disease; studies on cholesterol reduction however did not give evidence of any reduction in overall mortality. Alcohol displays an u-shaped relation between levels of assumption and associated mortality, depending on the fact that moderate drinkers show decreasing mortality scores and even a decreasing incidence of cardiovascular diseases (while the curve inflects upwards for serious drinkers). A direct correlation appears instead between both smoking and sedentary life on the one hand and both cardiovascular pathologies and mortality on the other. In order to reduce the risk factors' influence, on the ground of available studies and published trials do the authors offer practical indications. Fats in diet should be less than 30% of total calories (where of 10% saturated, 10% monounsaturated, 10% polyunsaturated); abstention from smoking must be absolute; alcohol should not exceed 15 g/die; some physical activity should be practised for 40-60 minutes, twice a week.

Alcohol Drinking↗
PubMed1992

hnRNP I, the polypyrimidine tract-binding protein: distinct nuclear localization and association with hnRNAs.

Many hnRNP proteins and snRNPs interact with hnRNA in the nucleus of eukaryotic cells and affect the fate of hnRNA and its processing into mRNA. There are at least 20 abundant proteins in vertebrate cell hnRNP complexes and their structure and arrangement on specific hnRNAs is likely to be important for the processing of pre-mRNAs. hnRNP I, a basic protein of ca. 58,000 daltons by SDS-PAGE, is one of the abundant hnRNA-binding proteins. Monoclonal antibodies to hnRNP I were produced and full length cDNA clones for hnRNP I were isolated and sequenced. The sequence of hnRNP I (59,632 daltons and pI 9.86) demonstrates that it is identical to the previously described polypyrimidine tract-binding protein (PTB) and shows that it is highly related to hnRNP L. The sequences of these two proteins, I and L, define a new family of hnRNP proteins within the large superfamily of the RNP consensus RNA-binding proteins. Here we describe experiments which reveal new and unique properties on the association of hnRNP I/PTB with hnRNP complexes and on its cellular localization. Micrococcal nuclease digestions show that hnRNP I, along with hnRNP S and P, is released from hnRNP complexes by nuclease digestion more readily than most other hnRNP proteins. This nuclease hypersensitivity suggests that hnRNP I is bound to hnRNA regions that are particularly exposed in the complexes. Immunofluorescence microscopy shows that hnRNP I is found in the nucleoplasm but in addition high concentrations are detected in a discrete perinucleolar structure. Thus, the PTB is one of the major proteins that bind pre-mRNAs; it is bound to nuclease-hypersensitive regions of the hnRNA-protein complexes and shows a novel pattern of nuclear localization.

Amino Acid Sequence↗
PubMed1990

Modeling by homology of RNA binding domain in A1 hnRNP protein.

Eukaryotic nuclear RNA binding proteins share a common sequence motif thought to be implicated in RNA binding. One of the two domains present in A1 hnRNP protein, has been modelled by homology in order to make a prediction of the main features of the RNA binding site. Acylphosphatase (EC 3.6.1.7) was selected as template for the modeling experiment. The predicted RNA binding site is a beta-sheet containing the two RNP consensus sequences as well as lysines and arginines conserved among the family.

Acid Anhydride Hydrolases↗
PubMed1990

Intermittent therapy with high-dose 5-aminosalicylic acid enemas for maintaining remission in ulcerative proctosigmoiditis.

Sixty patients who had presented recently with a relapse of mild to moderate ulcerative colitis with rectosigmoid involvement were randomly assigned to treatment with either 5-aminosalicylic acid enemas (N = 29) or oral sulfasalazine (N = 31). All patients were in remission, which was documented by clinical, histologic, and endoscopic criteria. Five-aminosalicylic acid treatment was administered on an intermittent schedule, consisting of 4 gm daily for the first seven days of each month; sulfasalazine was given as continuous therapy (2 gm daily as oral tablets). The study period was 2 years. Overall, 9 relapses occurred in the 5-aminosalicylic acid group and 12 occurred in the sulfasalazine group. The actuarial relapse rate at 12 months was 20 percent in the 5-aminosalicylic acid group and 24 percent in the sulfasalazine group; at 24 months, these rates were 37 and 43 percent, respectively. The actuarial relapse curves of the two groups were very similar. The relapse severity was also similar between the two groups. These results show that the authors proposed schedule of maintenance treatment with high-dose 5-aminosalicylic acid enemas is effective in subjects with rectosigmoiditis. This form of intermittent therapy may therefore be proposed for maintaining remission in patients who are refractory to oral and/or rectal treatment with sulfasalazine and steroids or who are intolerant or allergic to sulfasalazine. Treatment with 5-aminosalicylic acid enemas for seven days each month can also constitute an alternative for patients who favor the intermittent schedule over the classic continuous regimen of oral administrations.

Administration, Oral↗
PubMed1989

Secondary structure prediction for RNA binding domain in RNP proteins identifies beta alpha beta as the main structural motif.

In eukaryotic cells transcript processing is strictly dependent upon binding of specific proteins. Nuclear RNA binding proteins share a common domain, which is involved in RNA binding. In order to characterize RNP-RNA interactions we have performed a secondary structure prediction based both on statistical algorithms and comparative analysis of different proteins. A high conservation for secondary structure propensity between different RNPs was observed.

Amino Acid Sequence↗
PubMed1988

cDNA cloning of human hnRNP protein A1 reveals the existence of multiple mRNA isoforms.

Protein A1 is one of the major component of mammalian ribonucleoprotein particles (hnRNP). Human protein A1 cDNA cloning and sequencing revealed the existence of at least two protein isoforms. Among the cDNAs examined, sequence differences were found both in the structural portion, leading to aminoacid changes (Tyr to Phe or Arg to Lys) and in the non translated 3'-region where two T-stretches of different length were observed. Interestingly one of the aminoacid substitutions falls into a consensus sequence common to many RNA binding proteins. Northern blot analysis of poly A+ RNAs from five human tissues revealed two mRNA forms of 1500 and 1900 n due to alternative polyadenylation. Analysis of genomic DNA showed at least 30 A1-specific sequences, some of which correspond to processed pseudogenes. These results suggest that protein A1 is encoded by a multigene family.

Amino Acid Sequence↗