par Grenson, Marcelle 
Référence Biochimica et biophysica acta (G). General subjects, 127, 2, page (339-346)
Publication Publié, 1966-10
Référence Biochimica et biophysica acta (G). General subjects, 127, 2, page (339-346)
Publication Publié, 1966-10
Article révisé par les pairs
| Résumé : | 1. 1. The initial velocity of entrance of L-[14C]lysine into yeast cells appears, according to a Lineweaver-Burk plot, to be dependent on two functions. Evidence is presented showing that lysine enters the cell by two distinct systems. 2. 2. One of these systems is the arginine permease: it has been lost in the arg-p1 mutants (canavanine-resistant, arginine permease-less) and is specifically and competitively inhibited by L-arginine with a Ki of 10-5 M identical with the Km of arginine for its permease. Its apparent affinity constanct for lysine is about 2·10-4 M. 3. 3. The other lysine-uptake system has a higher affinity for lysine (Km, 2.5·10-5 M). IT is highly specific for lysine, as shown by competition experiments and by the fact that the loss of its activity by mutation (lys-P1) affects lysine uptake exclusively. 4. 4. It is concluded: (a) that a very specific lysine permease distinct and independent of the arginine permease exists in yeast; (b) that lysine may enter the cell by means of the arginine permease, while arginine cannot use the lysine permease. © 1966. |
