PubMed Health⌕ Search

Biomedical subjects

H C Pitot

Publications and source records attributed to H C Pitot.

At least 397 records · Page 22Linked to original sources
PubMed1973

Localization of polysome-bound albumin and serine dehydratase in rat liver cell fractions.

The polysomes involved in albumin and serine dehydratase synthesis were identified and localized by the binding to rat liver polysomes of anti-rat serum albumin and anti-serine dehydratase [(125)I]Fab dimer and monomer. Techniques were developed for the isolation of undegraded free and membrane-bound polysomes and for the preparation of [(125)I]Fab monomers and dimers from the IgG obtained from the antisera to the two proteins, rat serum albumin and serine dehydratase. The distribution of anti-rat serum albumin [(125)I]Fab dimer in the polysome profile is in accordance with the size of polysomes that are expected to be synthesizing albumin. By direct precipitation, it has been demonstrated that nascent chains isolated from the membrane-bound polysomes by puromycin were precipitated by anti-rat serum albumin-IgG at a level of 5-6 times those released from free polysomes. Anti-rat serum albumin-[(125)I]Fab dimer reacted with membrane-bound polysomes almost exclusively compared to the binding of nonimmune, control [(125)I]Fab dimer; a significant degree of binding of anti-rat serum albumin-[(125)I]Fab to free polysomes was also obtained. The [(125)I]Fab dimer made from normal control rabbit serum does not react with polysomes from liver at all and this preparation will not interact with polysomes extracted from tissues that do not synthesize rat serum albumin. Both anti-serine dehydratase-[(125)I]Fab monomer and dimer react with free and bound polysomes from livers of animals fed a chow diet or those fed a high 90% protein diet and given glucagon. In the latter instance, however, it is clear that the majority of the binding occurs to the bound polysomes. Furthermore, the specificity of this reaction may be further shown by the use of kidney polysomes that do not normally synthesize serine dehydratase. When these latter polysomes are isolated, even after the addition of crude and purified serine dehydratase, no reaction with anti-serine dehydratase-Fab fragments could be demonstrated. These results indicate that the reaction of the Fab fragments are specific for polysomes that synthesize rat serum albumin or rat liver serine dehydratase. Furthermore, they demonstrate that even with this high degree of specificity, some polysomes in the fraction labeled "free" are in the process of synthesizing rat serum albumin while bound polysomes to a significant, if not major, degree are the site of the synthesis of rat liver serine dehydratase.

Animals↗
PubMed1973

Influence of background genome on enzymatic characteristics of yellow (A v -, A vy -) mice.

Identification of the fundamental polypeptide difference between yellow (A(y)/-, A(vy)/-) and non-yellow mice is important for biomedical research because of the influence of the yellow genotype on normal and neoplastic growth and obesity. The complexity of the "yellow mouse syndrome" makes attainment of this objective dependent on the separation of those pleiotropic enzyme differences which are secondary, and depend on the background genome, from those which are primary, and depend primarily on the agouti locus genotype.-Four of nine hepatic enzyme activities assayed simultaneously differed between eight-week-old yellow (A(y)/-, A(vy)/-) and non-yellow (A/-, a/a) male inbred and F(1) hybrid mice. Among these four, only cytoplasmic malic enzyme activity was elevated in all yellow mice, as compared with the non-yellow sibs, regardless of background genome. Glucokinase, serine dehydratase, and tyrosine alpha-ketoglutarate transaminase activities were also changed in yellow mice, but these alterations depended on the background genome.-The ratio of malic enzyme activity to citrate-cleavage enzyme activity, possibly related to the altered fat metabolism of yellow mice, was influenced by background genome as well as by the yellow genotype.--Significant deviations of enzyme activities from mid-parent values among F(1) hybrids were associated with particular background genomes; the number of such deviations was larger among yellow mice than among non-yellows and this difference was greater among C3H F(1) hybrids than among C57BL/6 F(1) hybrids.

Ammonia-Lyases↗