A cAMP-binding protein from Dictyostelium discoideum regulates mammalian protein kinase

Ligand binding properties of the cytoplasmic cAMP‐binding protein of Dictyostelium discoideum

“…In the present report the structure of the CAMP The similarity in CAMP binding to the 40 K protein and the mammalian protein kinase regulatory subunit may suggest a structural relationship, which supports previous claims that a functional relationship exists, i.e., CAMP-dependent regulation of protein kinase activity [9,14]. The relatively fast dissociation kinetics of the 40 K protein allow this protein to respond to the short-term changes in CAMP concentration that occur during oscillation in D. discoideum [33], whereas the kinetics of the mammalian kinase allow response to only long term changes.…”

“…The 40 K CAMP binding protein is related to the regulatory subunits of mammalian protein kinase, since it is able to regulate mammalian kinase activity in a CAMP dependent manner [9]. In D. discoideum a CAMP dependent protein kinase was claimed [ Also a low-affinity CAMP binding protein was detected.…”

“…Part of the newly synthesized CAMP is secreted, part of it probably acts intracellularly. Intracellular CAMP is detected by a high-affinity CAMP binding protein, which has a Mr of 40 000 [6-121. This protein is present in much higher concentrations in differentiating than in vegetative cells [9,12].…”

Interaction of cAMP with the cell-surface receptor induces cell-type-specific mRNA accumulation in Dictyostelium discoideum.

“…Because of the continuous requirement for cAMP and the very high levels necessary for mRNA accumulation, the mechanism by which cAMP induces gene expression appears to differ from its role in directing chemotactic cell aggregation. A key question is whether cAMP induces the expression of these late genes by interacting at the cell-surface receptor or whether cAMP leaks into the cells and functions intracellularly as a "second messenger," possibly activating a cAMP-dependent protein kinase (8)(9)(10). Here we present evidence to indicate that cAMP functions to induce the accumulation of prespore and prestalk mRNA species by interacting at the cell-surface receptor.…”

Transmembrane signalling in eukaryotes: a comparison between higher and lower eukaryotes

“…5A; [199]). The pseudosubstrate domain is conserved, and Dictyostelium R subunits can form holoenzymes with mammalian C subunits [ 167]. Two potential cAMP-binding sites were found in the R subunit sequence, which was surprising since binding experiments indicated the presence of only one cAMP-binding site [64,59].…”