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Biomedical subjects

H M Kronenberg

Publications and source records attributed to H M Kronenberg.

115 records · Page 7Linked to original sources
PubMed1978

Parathyroid hormone biosynthesis: structure and function of biosynthetic precursors.

Investigations over the past several years have uncovered new information concerning the processes involved in the cellular formation of parathyroid hormone (PTH). Studies of parathyroid hormone biosynthesis in vitro using intact cell preparations as well as cell-free systems have led to: identification and characterization of a biosynthetic pathway for the formation of PTH involving successive proteolytic cleavages of the hormone from a larger polypeptide precursor; identification of the subcellular locations where the proteolytic processing of the precursors takes place; isolation of the messenger RNA for the hormone; and, finally, synthesis of functionally active gene copy of the parathyroid mRNA. It is now generally recognized that biosynthetic precursors and their post-translational modifications by proteolytic cleavages are characteristic of the biosynthetic processes involved in the formation of most if not all secretory proteins, not only parathyroid hormone and other polypeptide and protein hormones, but such diverse proteins as immunoglobulins, enzymes, and albumin. Furthermore, it is now evident that these biosynthetic precursors belong to two distinct classes, preproteins and proproteins, based on several criterions, including i) the time that elapses between synthesis of the precursor and the proteolytic conversion to the product, ii) the subcellular site at which the cleavages occur, iii) the specificity of the enzymic cleavage, and iv) the characteristics of the primary structures of the precursors.

Amino Acid Sequence↗
PubMed1977

DNA complementary to parathyroid mRNA directs synthesis of pre-proparathyroid hormone in a linked transcription-translation system.

DNA complementary in sequence to the messenger RNA for pre-proparathyroid hormone was synthesised using reverse transcriptase. In a linked transcription-translation system using RNA polymerase and cell-free extract from wheat germ, the DNA directed the synthesis of a protein identified as pre-proparathyroid hormone by N-terminal sequencing and by electrophoretic and immunologic criteria.

Amino Acid Sequence↗
PubMed1975

Vitellogenin synthesis in the avian liver. Vitellogenin is the precursor of the egg yolk phosphoproteins.

Administration of estrogen to roosters induces the synthesis of egg yolk phosphoproteins in the liver. We have demonstrated that these proteins are synthesized in the form of a large precursor, vitellogenin, and that vitellogenin is the only phosphoprotein found in the plasma of the estrogen-treated rooster. Vitellogenin is cleaved to form the egg yolk phosphoproteins, lipovitellin, and phosvitin. We have purified vitellogenin to hemogeneity by two methods: chromatography on diethylaminoethyl-52-cellulose and affinity chromatography on an antibody-Sepharose column. Antibodies were elicited in rabbits and sheep by immunization with vitellogenin and lipovitellin, and these antibodies were purified by affinity chromatography on antigen-Sepharose columns. We found that phosvitin was not immunogenic in its native form or in any of the large variety of modified forms we have tested. We have determined the molecular weights of native and denatured vitellogenin and have examined the immunological relationship between vitellogenin and lipovitellin. On the basis of these studies, together with data from phosphate analyses, we suggest that avian vitellogenin is composed of two polypeptides, each of which has a molecular weight of approximately 240,000 and contains within it lipovitellin and two phosvitins.

Animals↗
PubMed1975

Effect of estrogen on gene expression: purification of vitellogenin messenger RNA.

We report initial studies on estrogen-mediated regulation of egg yolk protein synthesis in the rooster. Egg yolk proteins are normally synthesized as a large precursor, vitellogenin, in the liver of the laying hen; roosters synthesize vitellogenin only when treated with estrogen. Polysomal RNA from the liver of estrogen-treated roosters was translated in a reticulocyte cell-free system, and the newly synthesized proteins were identified by a highly specific and sensitive indirect immunoprecipitation reaction. The messenger RNA that specifies vitellogenin has been purified more than 800-fold from rooster liver polysomal RNA by a combination of methods, including immunoprecipitation of polysomes and chromatography of RNA on poly(U)-Sepharose.

Animals↗