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J Mellor

Publications and source records attributed to J Mellor.

At least 73 records · Page 4Linked to original sources
PubMed1985

The Ty transposon of Saccharomyces cerevisiae determines the synthesis of at least three proteins.

Two new Ty determined proteins have been identified by placing a Ty transcriptional unit under the control of a high efficiency yeast expression vector. One of these proteins is the product of a post-translational processing event and it binds nucleic acids. A previously identified protein, pl (Tyl-15), has also been shown to bind nucleic acids and to be modified by phosphorylation.

Amino Acid Sequence↗
PubMed1985

Variants within the yeast Ty sequence family encode a class of structurally conserved proteins.

The Ty transposable elements of Saccharomyces cerevisiae form a heterogeneous family within which two broad structural classes (I and II) exist. The two classes differ by two large substitutions and many restriction sites. We show that, like class I elements a class II element, Tyl-17, also appears to contain at least two major protein coding regions, designated TYA and TYB, and the organisational relationship of these regions has been conserved. The TYA genes of both classes encode proteins, designated p1 proteins, with an approximate molecular weight of 50 Kd and, despite considerable variation between the TYA regions at the DNA level, the structures of these proteins are remarkably similar. These observations strongly suggest that the p1 proteins of Ty elements are functionally significant and that they have been subject to selection.

Amino Acid Sequence↗
PubMed1985

Factors affecting heterologous gene expression in Saccharomyces cerevisiae.

The 'promoter' fragment from the yeast phosphoglycerate kinase (PGK) gene has been used to direct the expression of human interferon-alpha-2 (IFN alpha 2) on a high-copy-number plasmid in yeast. The yields of IFN alpha 2 are only 1-3% of yeast total protein, whereas the maximum yield of PGK produced by the PGK gene on a high-copy-number plasmid is at least 50%. IFN alpha 2 is turned over more rapidly than PGK but in addition a major reason for the relatively low level of IFN alpha 2 is that IFN-specific RNA levels are much lower. This does not reflect differences in plasmid copy number or integrity, or differences in the 5' and 3' untranslated regions of the transcripts or DNA flanking regions. It appears that the presence of heterologous coding sequences, or the absence of specific yeast sequences causes a reduction in heterologous RNA levels in yeast.

Cloning, Molecular↗
PubMed1985

Serological failure of Pseudomonas vaccination in patients receiving multiple chemotherapy.

Patients undergoing induction chemotherapy for malignant disease were immunized with a polyvalent Pseudomonas vaccine using a three or four dose schedule. A control group was immunized with a two dose schedule. Despite the more intensive administration of vaccine to the patients they produce a markedly subnormal and brief antibody response. A large clinical trial of this vaccine in patients with cancer seems unjustified in light of these data.

Adolescent↗
PubMed1984

The identification and high level expression of a protein encoded by the yeast Ty element.

Transcription of the yeast Ty element, Ty1 -15, was placed under the control of the efficient PGK promoter on the yeast expression vector, pMA91 . In extracts of yeast transformants containing these constructions a new 52 K basic polypeptide was detected by one- and two-dimensional electrophoresis and was shown, by hybrid arrested translation, to be specifically encoded by the Ty element. The protein coding region was mapped to the first 1.45 kb of the transcribed region of Ty1 -15. These data show for the first time that Ty elements encode proteins and illustrate the general usefulness of high efficiency expression vectors for the detection of rare products.

Base Sequence↗
PubMed1983

Expression in Saccharomyces cerevisiae of human interferon-alpha directed by the TRP1 5' region.

The complete 5' flanking region of the yeast TRP1 gene encoding N-(5'-phosphoribosyl)- anthranilate isomerase, a nonabundant protein, has been cloned and the nucleotide sequence data has been extended from -102 to -440. The CT block--CAAG structure common to all efficiently expressed yeast genes is altered in the 5' region of TRP1 and a sequence postulated to be involved in general amino acid regulation is absent. There are two possible TATA boxes at -224 and -262. TRP1, in common with HIS3, HIS4 and TRP5 has a region of dyad symmetry upstream of the coding sequence which may play a role in initiation of transcription. The relative efficiency of gene expression directed by the complete 5' TRP1 region was assessed by comparison with that of PGK by inserting a cDNA for a human interferon-alpha downstream of their respective 5' regions. The respective interferon yields indicate that their in vivo expression capabilities are a function of their 5' regions.

Aldose-Ketose Isomerases↗
PubMed1983

Efficient synthesis of enzymatically active calf chymosin in Saccharomyces cerevisiae.

We have constructed a high-efficiency expression vector to direct the synthesis of heterologous polypeptides in yeast. The vector is termed a sandwich expression vector as the heterologous gene is inserted between the 5' and 3' control regions of the efficiently expressed yeast PGK gene. We have used this vector to direct the expression of three derivatives of the calf chymosin cDNA gene; preprochymosin, prochymosin and chymosin. Prochymosin is synthesised to at least 5% of total yeast-cell protein and furthermore, it can be readily activated to produce an enzyme which has milk-clotting activity.

Animals↗
PubMed1979

Co-ordination of the school and general dental services in Rochdale, England.

The administrative process in the implementation of a scheme of co-operation between the school and general dental practitioner services to screen and treat children aged 14 years and above in an Area Health Authority is described. 84% of the target group were screened in periods amounting to 12 months. The uptake of treatment as assessed by return of notices of referral was only 1.5%. Interview of a sample of those referred revealed that 49% had been to a dentist within 6 months and of these 34% would not have otherwise attended. 13% had taken referral forms to practitioners. The implications of these findings are discussed and a more effective means of evaluating treatment uptake is proposed.

Adolescent↗
PubMed1977

Re-activation.

Explore the source record for details and available documents.

Aged↗
PubMed1975

Macrophage arming factor release by allografted mouse lymphocytes stimulated by phytohermgglutinin.

Spleen cells from a C57BL/6 mouse allografted with DBA/2 skin may release a macrophage arming factor when stimulated with phytohemagglutinin. This in vitro nonspecific release is observed only when the recipient cells are collected during a limited period preceding or coinciding with graft rejection. The phenomenon disappears if the skin allograft has been removed before cell collection. It appears if an i.v. injection of donor cells is given to the recipient after graft removal, on the day preceding cell collection. These data suggest that this in vitro apparently nonspecific macrophage arming factor release by phytohemagglutinin-stimulated recipient cells may in fact disclose a previous specific in vivo immune cell triggering by graft antigens.

Animals↗
PubMedDate not supplied

A retrovirus-like strategy for expression of a fusion protein encoded by yeast transposon Ty1.

Eukaryotic transposons such as the Ty element of yeast or the copia-like sequences of Drosophila show structural and functional similarities to both prokaryotic transposons and retroviral proviruses, but the prokaryotic transposons and retroviral proviruses use markedly different expression strategies which yield products having entirely different functions. To determine the phylogenetic relationship between eukaryotic transposons, prokaryotic transposons and retroviruses, we have sought to identify and characterize the proteins encoded by the yeast Ty element and to describe the strategies used to express these proteins. We show here that the yeast transposon produces a fusion protein by a specific frameshifting event that fuses two out-of-phase open reading frames (ORFs). The process is remarkably similar to that used by retroviruses such as Rous sarcoma virus (RSV) to produce Pr180gag-pol.

Amino Acid Sequence↗
PubMedDate not supplied

Reverse transcriptase activity and Ty RNA are associated with virus-like particles in yeast.

The Ty element of yeast represents a class of eukaryotic transposons that show remarkable structural similarity to retroviral proviruses. Recently, these comparisons have been strengthened by a series of observations on the yeast Ty element: Ty transposes via an RNA intermediate; it contains a sequence (Fig. 1) which, when translated, is homologous to a conserved region found in all reverse transcriptases; a fusion protein encoded by Ty is produced by a frameshift event that is directly analogous to the production of Pr180gag-pol in a retrovirus such as Rous sarcoma virus. Here we identify the reverse transcriptase activity that, until now, has been presumed to mediate Ty transposition and show that it is sequestered in virus-like particles that also contain Ty RNA.

DNA Transposable Elements↗