Molecular cloning and analysis of the mouse homologue of the tumor-associated mucin, MUC1, reveals conservation of potential O-glycosylation sites, transmembrane, and cytoplasmic domains and a loss of minisatellite-like polymorphism.

We present here the full-length cDNA sequence and genomic structure of the mouse homologue of the tumor-associated mucin, MUC1. This mucin (previously called polymorphic epithelial mucin) is present at the apical surface of most glandular epithelial cells. The mouse gene, Muc-1, encodes an integral membrane protein with 40% of its coding capacity made up of serine, threonine, and proline, a composition typical of a highly O-glycosylated protein. The mucin core protein consists of an amino-terminal signal sequence, a tandem repeat domain encoding 16 repeats of 20-21 amino acids, and unique sequence containing transmembrane and cytoplasmic domains. Homology with the human protein is only 34% in the tandem repeat domain, mainly showing conservation of serines and threonines, presumed sites of O-linked carbohydrate attachment. Homology rises to 87% in the transmembrane and cytoplasmic domains, suggesting that these regions may be functionally important. The pattern of expression of the mouse mucin is very similar to that of its human counterpart and accordingly the two promoter regions share high homology, 74%, although previously identified potential hormone-responsive elements are not conserved. Interestingly, the mouse homologue, unlike its human counterpart does not exhibit a variable number tandem repeat polymorphism. We present evidence that suggests that the mouse gene was at one time polymorphic but has mutated away from this state.     

Xanthoxin levels and metabolism in the wild-type and wilty mutants of tomato

Using ¹³C-labelled internal standards and gas chromatography-mass spectrometry/multiple-ion monitoring the levels of xanthoxin (Xan) and 2-trans-xanthoxin (t-Xan) have been determined in stressed and non-stressed leaves of wildtype tomato (Lycopersicon esculentum Mill cv. Ailsa Craig), and the wilty mutants, notabilis (not), flacca (flc) and sitiens (sit). Levels of Xan were very low in all tissues. Ratios of t-Xan: Xan ranged from 10:1 to <500:1. In the wild-type and flc, t-Xan levels increased following stress. The results from feeding experiments using [¹³C]Xan and t-Xan demonstrated that whilst wild-type and not plants readily converted Xan into abscisic acid (ABA), flc and sit plants converted only a small amount of applied Xan into ABA. In all plants t-Xan was not converted into ABA. These results indicate that the flc and sit mutants are impaired in ABA biosynthesis because they are unable to convert Xan into ABA, whereas the not mutant is blocked at a metabolic step prior to Xan. Another possible ABA precursor, ABA-1,4-trans-diol (ABA-t-diol) was found to occur in wild-type and mutant tissue. All four tissues could convert [²H]ABA-t-diol to ABA. Incubation of stressed leaves in the presence of ¹⁸O₂ provided evidence consistent with Xan and ABA originating via oxidative cleavage of a xanthophyll such as violaxanthin.Abbreviations ABA abscisic acid - ABA-t-diol abscisic acid-1,4-trans-diol - DDC sodium diethyldithiocarbamate - FW fresh weight - GC-MS gas chromatography-mass spectrometry - i.d. internal diameter - MIM multiple-ion monitoring - PA phaseic acid - Xan xanthoxin - flc flacca - not notabilis - sit sitiens     

Toward the development of potent and selective bisubstrate inhibitors of protein arginine methyltransferases

Prototype inhibitors of protein arginine methyltransferases (PRMTs) have been constructed by attaching guanidine functionality via a variable linker to non-reactive amine analogues of the cellular co-factor (S)-adenosyl methionine (AdoMet). Potent inhibition of PRMT1 (IC₅₀ of ～3–6 μM) combined with weak inhibition of the lysine methyltransferase SET7 (～50% of activity at 100 μM) was observed for two such compounds.     

Altered Rubisco activity and amounts of a daytime tightbinding inhibitor in transgenic tobacco expressing limiting amounts of phosphoribulokinase

Transgenic tobacco with RuBP-limited photosynthetic assimilationdue to a 95% reduction in phosphoribulokinase activity, hadhigher specific activities of Rubisco in fresh extracts andafter full activation, than in the wild type. Differences inthe amounts of a daytime tight-binding inhibitor were sufficientto contribute significantly to these activity differences. Key words: Nicotiana tabacum, transgenic plant, phosphoribulokinase, Rubisco, tight-binding inhibitor     

Translational fusions with fragments of the trpE gene improve the expression of a poorly expressed heterologous gene in Escherichia coli

A series of plasmids expressing fusions between the trpE gene product, anthranilate synthase component I and the major immunogen (VP1) of foot and mouth disease virus were constructed such that increasing amounts of the 3' end of trpE were deleted. Deletions removing up to 70% of trpE had little effect on the quantity of fusion protein expressed, while the number of molecules appeared to increase. Larger deletions led to a steady decrease in both the quantity of fusion protein produced and in the number of molecules. This is consistent with trpE being responsible for the high levels of expression of VP1 by its gene product stabilizing VP1 against proteolytic degradation. Some out-of-frame deletion mutants were also produced. All deletion mutants in one wrong reading frame expressed low levels of two VP1-containing polypeptides. This observation is interpreted as being due to re-initiation of translation at a site inside the VP1 sequence which is activated by local termination of translation.     

Collagen fibril morphology in developing chick metatarsal tendoms: 1. X-ray diffraction studies

The low angle equatorial X-ray diffraction ($\text{R ? 30 μ}\text{m}{}^{\mathrm{?1}}$) from hydrated embryonic chick metatarsal tendon contains minima and maxima that are not seen in mature tendons. This diffraction derives from the disordered array of parallel, cylindrical fibrils of collagen of small, uniform diameter that comprise the major part of this tissue. Comparison of the positions of the minima and maxima with those expected from an array of cylinders allows estimation of the mean diameter of the cylinders and the average centre-to-centre nearest neighbour separation. It was found that in the age range from 13 to 19 days fetal, the mean diameter increased from ～ 46 to ～ 58 nm, whereas the mean nearest neighbour separation remained constant at ～ 90 nm. Detailed analysis of the X-ray intensity profile of a 17 day fetal tendon indicated the presence of a paucidisperse distribution of fibril diameters with two or more discrete populations of preferred diameters separated by 10 to 12 nm.