Acetylcholine (ACh)- and high KCl-stimulated 45Ca uptake into rat uterine segments was inhibited by 3-deazaadenosine (3-DAA) plus homocysteine thiolactone (HCTL), and this inhibitory effect was attenuated by L-methionine (L-Met). Ca-depleted Ringer solution in which uterine muscle had been incubated with L-Met did not enhance the contractile response of another uterine segment to ACh and high K...

Evidence is presented that the editing mechanisms of aminoacyl-tRNA synthetase operate by two alternative pathways: pre-transfer, by hydrolysis of the non-cognate aminoacyl adenylate; post-transfer, by hydrolysis of the mischarged tRNA. The methionyl-tRNA synthetases from Escherichia coli and Bacillus stearothermophilus and isoleucyl-tRNA synthetase from E. coli, for example, are shown to rejec...

Homocysteine (hcy) is an intermediate metabolite in the metabolic pathway of cysteine and methionine. As a non-coded amino acid, hcy is not normally incorporated into protein. However, homocysteine can be recognized and activated by methionyl-tRNA synthetase (MetRs) to produce Hcy-thiolactone (HTL), which can react with the ε-amino group of a protein lysine residue. The N-hcy-linked protein car...

Four classes of agents capable of producing human illness have been identified: toxicity, heredity, infection and deficiency. The leading paradigm for the etiology and pathophysiology of ischemic heart disease in the 20th century was that of intoxication by too much of the wrong kind of dietary fat. This overemphasis on lipid metabolism persists because important data are neglected and because ...

The present study was undertaken to investigate a possible involvement of phospholipid methyltransferases in the coupling of receptor-mediated stimulation to secretion. Phospholipid methyltransferases were assayed in isolated parotid acini in the presence of carbamoylcholine or isoprenaline. Carbamoylcholine reduced the incorporation of methyl groups into phospholipids, whereas isoprenaline sho...