Insulin stimulus of leucine incorporation into frog liver protein

Slices prepared from livers of bull frogs ( Rana catesbiana), pancreatectomized and/or hypophysectomized 7 days before, were incubated 2 hr in frog Ringer-bicarbonate solution at 25 C. Incorporation of leucine-1-C14 into protein was subnormal in the pancreatectomized series. The addition of insulin in vitro, with glucose also present in the medium, produced a significant ( P < 0.01) stimulation of amino acid incorporation in the following series: livers from normal fed animals; livers from animals pancreatectomized 7 days before; and livers from animals pancreatectomized and hypophysectomized 7 days before. Neither insulin nor glucose alone gave a significant effect. These results therefore confirm and extend those obtained with rat liver slices showing that insulin can stimulate amino acid incorporation into protein when added directly to liver. The effect is relatively greatest with livers from animals pancreatectomized 7 days before; the insulin effect does not depend on the presence of the pituitary, as it is obtainable with livers from animals hypophysectomized and pancreatectomized 7 days previously.

Download Full-text

Insulin stimulus of leucine incorporation in rat liver protein

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1962.202.2.349 ◽

1962 ◽

Vol 202 (2) ◽

pp. 349-352 ◽

Cited By ~ 29

Author(s):

J. C. Penhos ◽

M. E. Krahl

Keyword(s):

Amino Acid ◽

Rat Liver ◽

Leucine Incorporation ◽

Liver Protein ◽

Amino Acid Incorporation ◽

Experimental Conditions ◽

Maximum Percentage ◽

Acid Incorporation ◽

Liver Slices

Slices were prepared from livers of partially pancreatectomized rats and incubated 2 hr in Krebs bicarbonate solution at 37 C. Incorporation of leucine-1-C14 into protein decreased progressively as severity of diabetes increased during 1–6 months after operation; at 2–4 months insulin (0.01 U/ml of medium) plus glucose (200 mg/100 ml) added in vitro stimulated incorporation 62–78%; stimulation was not significant at 6 months. Neither insulin nor glucose was effective separately. Alkali-inactivated insulin was ineffective, even with glucose. Liver slices from sham-operated rats responded similarly to insulin under the present experimental conditions, although the maximum percentage stimulation was smaller than in the partially pancreatectomized series. It is concluded that insulin can act directly on the liver to stimulate amino acid incorporation in protein by a mechanism dependent on the presence of glucose.

Download Full-text

Biotin-mediated protein biosynthesis

Biochemical Journal ◽

10.1042/bj1400549 ◽

1974 ◽

Vol 140 (3) ◽

pp. 549-556 ◽

Cited By ~ 24

Author(s):

R. L. Boeckx ◽

K. Dakshinamurti

Keyword(s):

Protein Synthesis ◽

Amino Acid ◽

Rat Liver ◽

Intestinal Mucosa ◽

Protein Biosynthesis ◽

Amino Acid Incorporation ◽

Acid Incorporation ◽

Stimulation Of

The effect of administration of biotin to biotin-deficient rats on protein biosynthesis was studied. Biotin treatment resulted in stimulation by more than twofold of amino acid incorporation into protein, both in vivo and in vitro in rat liver, pancreas, intestinal mucosa and skin. Analysis of the products of amino acid incorporation into liver proteins in vivo and in vitro indicated that the synthesis of some proteins was stimulated more than twofold, but others were not stimulated at all. This indicates a specificity in the stimulation of protein synthesis mediated by biotin.

Download Full-text

THYROXINE STIMULATION OF AMINO ACID INCORPORATION INTO MITOCHONDRIAL PROTEIN: DIFFERENCES BETWEEN IN VIVO AND IN VITRO EFFECTS

Acta Endocrinologica ◽

10.1530/acta.0.0720684 ◽

1973 ◽

Vol 72 (4) ◽

pp. 684-696 ◽

Cited By ~ 25

Author(s):

Amirav Gordon ◽

Martin I. Surks ◽

Jack H. Oppenheimer

Keyword(s):

Protein Synthesis ◽

Amino Acid ◽

Mitochondrial Protein ◽

Leucine Incorporation ◽

Mitochondrial Protein Synthesis ◽

Amino Acid Incorporation ◽

Acid Incorporation ◽

Stimulation Of

ABSTRACT The in vivo and in vitro stimulation of rat hepatic mitochondrial protein synthesis by thyroxine (T4) was compared. In confirmation of Buchanan & Tapley (1966). T4 added to isolated mitochondria rapidly stimulated [14C] leucine incorporation into mitochondrial protein. The in vitro stimulation was reversed after T4 was removed by incubating the mitochondria with bovine serum albumin (BSA). The decrease in T4 stimulation of protein synthesis appeared proportional to the T4 removed by BSA. Thus, it appears probable that exchangeable T4 controls the in vitro system. In contrast, the increase in mitochondrial protein synthesis which was observed 3 to 4 days after pretreatment of hypothyroid rats with labelled and non-radioactive T4 was not reversed by BSA treatment. Moreover, mitochondrial radioactivity could not be extracted with albumin. The in vivo phenomenon does not, therefore, appear to be related to exchangeable hormone in the mitochondria. Furthermore, the estimated quantity of T4 associated with mitochondria after in vivo stimulation was at least two orders of magnitude less than that required to produce comparable stimulation of mitochondrial protein synthesis in vitro. These findings strongly suggest that in vitro and in vivo stimulation of amino acid incorporation by T4 may be mediated by different biochemical mechanisms.

Download Full-text