A tripeptide 'anticodon' deciphers stop codons in messenger RNA

The two translational release factors of prokaryotes, RF1 and RF2, catalyse the termination of polypeptide synthesis at UAG/UAA and UGA/UAA stop codons, respectively. However, how these polypeptide release factors read both non-identical and identical stop codons is puzzling. Here we describe the basis of this recognition. Swaps of each of the conserved domains between RF1 and RF2 in an RF1-RF2 hybrid led to the identification of a domain that could switch recognition specificity. A genetic selection among clones encoding random variants of this domain showed that the tripeptides Pro-Ala-Thr and Ser-Pro-Phe determine release-factor specificity in vivo in RF1 and RF2, respectively. An in vitro release study of tripeptide variants indicated that the first and third amino acids independently discriminate the second and third purine bases, respectively. Analysis with stop codons containing base analogues indicated that the C2 amino group of purine may be the primary target of discrimination of G from A. These findings show that the discriminator tripeptide of bacterial release factors is functionally equivalent to that of the anticodon of transfer RNA, irrespective of the difference between protein and RNA.     

High-speed countercurrent chromatography

Support-free high-speed countercurrent liquid chromatography provides a rich domain of applications, some beyond reach of conventional liquid chromatography.     

Electronic Structure and Electron-transport Properties of Peanut-shaped C60 Polymers with a Negative Gauss Curvature

1 Results When a C60 film was irradiated with electron-beam (EB) with an incident energy of 3 kV, a peanut-shaped C60 polymer with metallic properties was formed[1], as shown in Fig.1. To elucidate the origin of the metallic properties of the peanut-shaped polymer, we examined the valence photoelectron spectra of the polymer using in situ high-resolution photoelectron spectroscopy and found that the electronic states of the polymer came across the Fermi level (EF)[2]. Interestingly, the spectral shape i...     

Cardiac hypertrophy in surgically denervated dogs with aortic stenosis

Summary Left ventricular cell hypertrophy in dogs with aortic stenosis was accelerated by surgical denervation of the left ventricle. We conclude that there are neural mechanisms which, when present, inhibit cardiac cell hypertrophy.This work was supported by a grant of the Ministry of Education in Japan for 1981.     

Intracellularly recorded antidromic responses of deiters' neurones

Résumé Chez le chat anesthésié au Nembutal, les réponses évoquées dans les neurones de Deiters par les stimulations antidromiques ont été étudiées au moyen de microélectrodes intracellulaires.     

The in vitro effect of adrenergic agents and related compounds on triglyceride levels of guinea-pig lymphoid cells.

Isoproterenol, epinephrine and norepinephrine were highly potent in decreasing the triglyceride levels of the splenic lymphoid cells from guinea-pigs in vitro, while they were quite inert upon the inguinal lymph node cells.