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Biomedical subjects

I Pastan

Publications and source records attributed to I Pastan.

At least 811 records · Page 45Linked to original sources
PubMed1970

Radioreceptor assay of adrenocorticotropic hormone: new approach to assay of polypeptide hormones in plasma.

Biologically active iodine-125-labeled adrenocorticotropic hormone (ACTH) binds specifically to ACTH receptors extracted from adrenals. Unlabeled ACTH at 1 picogram per milliliter significantly displaces labeled ACTH from these receptors. This system, which appears to be applicable to all polypeptide hormones, provides a rapid and sensitive method for measurements of biologically active ACTH in dilute whole plasma.

Adrenal Glands↗
PubMed1970

Cyclic adenosine monophosphate in bacteria.

Both cyclic AMP and a specific inducer acting in concert are required for the synthesis of many inducible enzymes in E. coli. Little enzyme is made in the absence of either. In contrast to the specific inducers which stimulate the synthesis only of the proteins required for their metabolism, cyclic AMP controls the synthesis of many proteins. Glucose and certain other carbohydrates decrease the differential rate of synthesis of inducible enzymes by lowering cyclic AMP concentrations. In the lac operon, cyclic AMP acts at the promoter site to facilitate initiation of transcription. This action requires another protein, the cyclic AMP receptor protein. The nucleotide stimulates tryptophanase synthesis at a translational level. The action of cyclic AMP in E. coli may serve as a model to understand its action on transcriptional and translational processes in eukaryotes.

Adenine Nucleotides↗
PubMed1970

Mechanism of action of 2-mercapto-1(beta-4-pyridethyl)benzimidazole: a reversible inhibitor of interferon activity.

2-mercapto-1(beta-4-pyridethyl)benzimidazole (MPB) inhibited the development of antiviral activity induced by interferon in chick cells. The MPB effect was reversed by washing the cells. The action of MPB was on a step immediately following interferon binding but before the cellular RNA and protein synthesis that appear to be required for interferon action. The step blocked by MPB possibly involves cellular phospholipid synthesis.

Animals↗
PubMed1970

ACTH receptors in the adrenal: specific binding of ACTH-125I and its relation to adenyl cyclase.

Pure monoiodo ACTH-(125)I was prepared that was biologically active and free of unlabeled ACTH. Extracts of adrenal cortex that contained ACTH-sensitive adenyl cyclase, bound ACTH-(125)I; extracts that lacked the ACTH-sensitive cyclase did not bind ACTH-(125)I. Unlabeled ACTH inhibited the binding of ACTH-(125)I. Five ACTH derivatives which varied widely in biological activity were tested. All inhibited the binding of ACTH-(125)I in direct proportion to their biological activity. Albumin, insulin, and four unrelated iodinated hormones were inert. The addition of excess hormone or acetic acid produced rapid dissociation of bound ACTH-(125)I. This study demonstrates directly the binding of ACTH to its biologically significant site.

Adenylyl Cyclases↗
PubMed1970

Cyclic AMP receptor protein of E. coli: its role in the synthesis of inducible enzymes.

A cyclic AMP binding protein has been purified over 100-fold from E. coli extracts. Protein purified from wild-type strains binds cyclic AMP with an apparent dissociation constant of 1-2 x 10(-6)M. Two mutant strains that are unresponsive to exogenous cyclic AMP have altered binding activity; the protein purified from one of these mutants has a decreased affinity for cyclic AMP (apparent dissociation constant = 2 x 10(-5)M). Extracts of this mutant are deficient in their ability to support beta-galactosidase synthesis in vitro. The addition of purified, wild-type binding protein to these extracts restores enzyme synthesis toward normal. Because this binding protein appears to be required for cyclic AMP action, we suggest it be called the cyclic AMP receptor protein (CR protein).

Adenine Nucleotides↗