Decreases in calmodulin binding proteins and calmodulin dependent protein phosphorylation in the medial preoptic area at the onset of maternal behavior in the rat.

The onset of maternal behavior is characterized by the action of certain hormones, neuropeptides and neurotransmitters and a concomitant increase in the expression of c-Fos in the medial preoptic area (MPOA) but the signaling events that lie between have not been characterized. Because several of these hormones, neuropeptides and neurotransmitters function by activating Ca(2+)/calmodulin (CaM) mediated signaling pathways, many of which can lead to c-Fos expression, the goal of the current work was to identify calmodulin binding proteins (CaMBPs) or specific CaM-dependent phosphoproteins that might be involved. Probing of SDS-PAGE gels of extracts from the hippocampus, parietal cortex, basolateral amygdala and MPOA with recombinant (35)S-VU1-calmodulin (CaM) revealed 30 Ca(2+)-dependent and 4-6 Ca(2+)-independent CaMBPs.

Endogenous autoinhibitors regulate changes in actin tyrosine phosphorylation during Dictyostelium spore germination.

Phosphorylation of proteins on tyrosine residues has been shown to govern many cellular processes, but little work has focused on the role of tyrosine phosphorylation during germination. Under optimal conditions, D. discoideum spores synchronously germinate each liberating a single amoeba.

Fertilization in Dictyostelium: pharmacological analyses and the presence of a substrate protein suggest protein kinase C is essential for gamete fusion.

The role of protein kinase C (PKC) during fertilization in the model eukaryote Dictyostelium discoideum was studied. Inhibition of PKC activity using staurosporine, chelerythrine, and bisindoylmaleimide resulted in a dose-dependent decrease in gamete fusion without any detectable effect on cell morphology or growth. At 1.

The role of Ca2+ during spore germination in Dictyostelium: autoactivation is mediated by the mobilization of Ca2+ while amoebal emergence requires entry of external Ca2+.

One of the developmental pathways used by the social amoeba Dictyostelium discoideum produces dormant spores. As with any temporary resistant stage, these spores must be able to germinate rapidly in response to positive environmental stimuli. One such stimulus is the autoactivator, an endogenous, diffusible molecule that is secreted by spores.

Calmodulin function and calmodulin-binding proteins during autoactivation and spore germination in Dictyostelium discoideum.

Dictyostelium discoideum spores can be activated to initiate germination either endogenously via a diffusible autoactivator, or exogenously via heat. Following activation, three successive stages of germination occur, the lag stage, spore swelling and amoebal emergence. A previous study [Lydan M.