The role of calcium ions (Ca2+) in cell function is beginning to be unraveled at the molecular level as a result of recent research on calcium-binding proteins and particularly on calmodulin. These proteins interact reversibly with Ca2+ to form a protein . Ca2+ complex, whose activity is regulated by the cellular flux of Ca2+. Many of the effects of Ca2+ appear to be exerted through calmodulin-regulated enzymes.

Calmodulin plays a pivotal role in cellular regulation

Adenosine 3',5'-phosphate in biological materials. I. Purification and properties of cyclic 3',5'-nucleotide phosphodiesterase and use of this enzyme to characterize adenosine 3',5'-phosphate in human urine.

The hypothesis advanced in this article requires further validation. Undoubtedly it will require modification as our knowledge of biochemical control increases. Nevertheless, it should prove useful in focusing attention on the apparent similarity in the response of a large number of specific cell types to particular stimuli. Emphasis has been placed on a few common and apparently key elements in these responses. It is recognized that other factors are undoubtedly involved. Specifically, the changes in membrane potentials indicate the likelihood of widespread changes in the properties of the cell membrane, for example, changes in Na(+) and K(+) transport and distribution. These aspects of cellular responses may eventually prove to be of equal or greater importance than those common aspects of the system already identified.

Cell Communication, Calcium Ion, and Cyclic Adenosine Monophosphate

Fractionation and characterization of a cyclic adenine ribonucleotide formed by tissue particles

Cyclic AMP (adenosine 3',5'-monophosphate or cyclic adenylate) has now been established as a second messenger mediating many of the effects of a variety of hormones. Several of the metabolic effects mediated by cyclic AMP are discussed, and it is suggested that certain other ("functional" or "mechanical") hormonal effects may be similarly mediated. In particular, the evidence presented supports the hypothesis that the positive inotropic response to the catecholamines is mediated by cyclic AMP. Although knowledge of the biological role of cyclic AMP has not been widely applied clinically, sufficient knowledge has now accumulated to make research in this area desirable.

Some Aspects of the Biological Role of Adenosine 3',5'-monophosphate (Cyclic AMP)

The relationship of epinephrine and glucagon to liver phosphorylase iv. effect of epinephrine and glucagon on the reactivation of phosphorylase in liver homogenates

Jacques Berthet

Papers

The relationship of epinephrine and glucagon to liver phosphorylase iv. effect of epinephrine and glucagon on the reactivation of phosphorylase in liver homogenates

The assay of glucagon and epinephrine with use of liver homogenates.

Observations on the action of certain sulfonylurea derivatives.