Search PubMed⌕ Search

Biomedical subjects

I Pastan

Publications and source records attributed to I Pastan.

At least 775 records · Page 43Linked to original sources
PubMed1973

Cyclic adenosine monophosphate receptor: loss of cAMP-dependent DNA binding activity after proteolysis in the presence of cyclic adenosine monophosphate.

The cAMP receptor requires cAMP for DNA binding at pH 8.0 but shows cAMP-independent DNA binding at pH 6.0. Incubation of the cAMP receptor with proteolytic enzymes in the presence of cAMP results in loss of DNA-binding ability at pH 8, while it is still able to bind cAMP and DNA at pH 6. Incubation with proteolytic enzyme in the absence of cAMP does not affect the DNA-binding properties of the cAMP receptor. After proteolysis in the presence of cAMP, analysis by sodium dodecyl sulfateacrylamide-gel electrophoresis shows that the 22,500-dalton subunit characteristic of the untreated protein has been completely replaced by a 12,500-dalton fragment.

Adenine Nucleotides↗
PubMed1972

Cyclic AMP.

Explore the source record for details and available documents.

Cell Membrane↗
PubMed1972

Isolation and characterization of myosin from cloned mouse fibroblasts.

Myosin has been isolated from cloned mouse fibroblasts, line L-929. Fibroblast myosin: (i) binds to rabbit muscle actin and is dissociated from it by ATP, (ii) has an ATPase activity that is suppressed by Mg(2+) in 0.6 M KCl and is activated by rabbit muscle actin in the presence of Mg(2+) in 14 mM KCl, (iii) forms thin bipolar aggregates in 0.1 M KCl when viewed in the electron microscope, (iv) possesses a heavy chain with the same mobility as muscle myosin (molecular weight 200,000) in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In these respects, fibroblast myosin appears to be similar to muscle myosin in structure and function.

Actins↗
PubMed1972

Regulation of adenosine 3',5'-cyclic monophosphate phosphodiesterase activity in fibroblasts by intracellular concentrations of cyclic adenosine monophosphate (3T3-dibutyryl cyclic AMP-SV40-transformed cells-michaelis constants-L cells-prostaglandin E 1 ).

Cyclic AMP-phosphodiesterase is present in various mouse fibroblasts. Contact-inhibited 3T3 cells contain two forms of the enzyme, one with a K(m) of 2.5 muM and the second with a K(m) of 71 muM. As 3T3 cells grow to confluency and cAMP concentrations rise, the activity of the first enzyme increases, whereas that of the second is unchanged. A line of SV40-transformed 3T3 cells with low cAMP concentration also has low levels of the cAMP-phosphodiesterase with a K(m) of 2.5 muM. Treatment of 3T3 and SV40-transformed 3T3 cells with dibutyryl cAMP and theophylline increases cAMP-phosphodiesterase accumulation. This accumulation is blocked by cycloheximide and actinomycin D. The newly formed enzyme resembles the higher affinity enzyme present in unstimulated cells, since it has a K(m) of 1.2-2.0 muM, and is stimulated by snake venom. In L cells in which cAMP concentrations are elevated by treatment with prostaglandin E(1), cAMP phosphodiesterase also accumulates. We conclude that intracellular concentrations of cAMP regulate the synthesis of cAMP-phosphodiesterase, and that cAMP functions as an inducer of the enzyme.

Animals↗
PubMed1972

Clostridium barkeri sp. n.

Clostridium barkeri sp. n. has been described, and its relationship to other clostridia is discussed.

Acetates↗