Cadherins are transmembrane glycoproteins involved in Ca2+-dependent cell-cell adhesion. Using L cells expressing one of three functional E-cadherin constructs, the wild-type, a chimeric molecule with alpha-catenin (EalphaC), and a tail-less one, we determined the effect of v-Src expression on E-cadherin-mediated adhesion. The aggregation of L cells expressing the wild-type or EalphaC chimeric ...

Liver disease is associated with an abnormal elevation of the plasma concentrations of the aromatic amino acids phenylalanine and tyrosine. The liver is the main site of aromatic amino acid metabolism, particularly the hydroxylation of phenylalanine to tyrosine and further tyrosine degradation. In the present study, we have examined the usefulness of the L-[1-13C]phenylalanine breath test (13C-...

Young leaves of tropical forest trees experience far higher herbivory pressure than mature leaves of the same species. Selection on young leaves has led to diverse forms of defense chemical expression. Though most allelochemicals are secondary metabolites, allelochemic function for a primary metabolite remains a possibility. We recently observed this phenomenon in the young leaves of Inga umbel...

Experiments were performed to test the hypothesis that tyrosine kinase activity contributes to renal arteriolar contractile responses to angiotensin (Ang) II. Rats were subjected to short-term enalaprilat treatment to decrease endogenous Ang II formation before tissue was harvested for experiments with the in vitro blood-perfused juxtamedullary nephron technique. Acute surgical papillectomy was...

background: the hepatic secretion of apolipoprotein b (apob), containing lipoproteins, is known to be regulated by insulin, and the overproduction of these atherogenic lipoproteins occurs in insulin-resistant states. protein tyrosine phosphatase 1b (ptp-1b) is a key regulator of hepatic insulin signaling and is also upregulated in insulin resistance. we aimed to investigate the role of ptp-1b i...

protein tyrosine phosphatases (ptpases) regulate the tyrosine phosphorylation of target proteins in volved in several biological activities including cell proliferation and transformation. protein tyrosine phosphatase e (ptpe) contains duplicated ptpase-like domains and a short extracellular region. us ing the fluorescence in situ hybridization method, the gene encoding ptpe (locus symbol ptpre...

Recent studies in vitro of tyrosine metabolism have revealed the distribution and the r&e of the tyrosine-a-ketoglutaric acid transaminase system (l-8). In certain of these studies the obligatory rBle of this transaminase as a first step in the conversion of tyrosine to homogentisic acid has been indicated (6-S). The present study is concerned with the partial purification of dog liver tyrosine...

The incorporation of [(14)C]phenylalanine and [1,6-(14)C]shikimic acid into tyrosine was investigated in the callus of Portulaca grandiflora, var. JR (L.). By inhibiting phenylalanine with 1-alpha-aminooxy-beta-phenyl-propionic acid and tyrosinase with 1-cysteine-HCl and hydrazine-hydrate, the possible synthesis of tyrosine from phenylalanine was demonstrated. Tetrahydropterine sulfate was an e...

An assay of L-tyrosine (Tyr) hydroxylating activity operating in lincomycin biosynthesis is described. The assay development consisted of HPLC procedure development, assessing the effect of reaction mixture components on non-enzymatic Dopa and Tyr oxidation, and sample stability evaluation. The HPLC procedure with isocratic elution and fluorescence detection was developed and validated. The met...